This article contains manga details that are not covered in the anime. Do not proceed unless you want to be spoiled.
|Alias||Ouryuu (黄龍 Ōryū)|
|Birthday||August 30 (Virgo)|
|Previous Occupation||First Priest of Kouka|
Ex Chief and Founder of the Sky Tribe 
|Previous Partner(s)||King Hiryuu|
|Relatives||Kaya (Wife, deceased)|
|Manga Debut||Chapter 42|
|Anime Debut||Episode 24|
|Japanese Voice||Hiro Shimono|
|English Voice||Josh Grelle|
Zeno (ゼノ Zeno) is the Ouryuu, one of the four dragon warriors, which possesses the blood of the yellow dragon deity. Later, it is revealed that he is actually the original Ouryuu who once served King Hiryuu.
In the anime (manga chapter 1-109) Zeno is shown/known as a young man who always has a smile on his face, which indicates that he is a cheerful person. He has blue eyes (previously brown) and thick, messy yellow hair. 2000 years ago, King Hiryuu gave Zeno a necklace of alternating, round burgundy and blue oblong beads with the centrepiece being a golden disc with a dragon on it. Originally, Zeno wore it as an ordinary necklace but currently wears it around his head, under his bandana, with the disc hanging out on the left side of his head, in front of his ear.He is considered very handsome.
He wears an orange overcoat with diamond patterns on top of a white robe with brown hemlines, fastens a green scarf around his neck, and dons brown short boots.
When Zeno's powers are activated, the part of his body that regenerates becomes covered in yellow scales, also temporarily giving him powers similar to Kija if his arm regenerates and Jae-Ha if his legs regenerate.
Zeno is an energetic, cheerful young man who enjoys the company of others. He mostly uses third-person speech and rarely calls anybody by their given names even after learning them (he calls the dragons by their titles, ex: Seiryuu or Ryokuryuu) Most of the time, he appears to be childish and rather attention-seeking, though he has his wise and mature moments, being 2000+ years old. Despite the fact that he chooses not to fight, he always stands on the front lines to protect everyone from danger.
Like Jae-Ha, he can easily discern what is happening to a person and even has foresight on them, like when he tells Hak that he has "the smell of death" on him or how he says that Tae-Jun has changed and that he can become someone important. He also appears to know more than what he is willing to tell and may appear deceitful because of it. However, he actually waits for the right time to tell things as he can’t easily show or express it to others given his circumstances of being one of the original dragon warriors.
Zeno can be very lovable, and at times he tends to try to break up Kija and Hak's arguments. He especially loves food, which is what first got him in to the group in the middle of a forest, before the other dragons revealed his identity. According to Hak, Zeno "broke Kija's record of speed joining".
Two thousand years ago, Zeno was just an ordinary kid who could hear the voice of God like Ik-Soo. When Ouryuu descended from the heavens to look for a human who can be his other half, Zeno decided to take in the dragon’s blood in a wish to make the world a better place and for everyone to be happy. Since then, he has stopped ageing and no longer hears the voice of God.
He joined Gu-En, Abi and Shu-Ten, who were the Hakuryuu, Seiryuu and Ryokuryuu, respectively. During the conflict in Kouka, the four of them protected King Hiryuu. One time, the other dragon warriors became curious of Zeno's powers and he showed them how he is able to regenerate fast. When he showed it to King Hiryuu, he was hugged by him and was given a dragon crest. Several days after, he became worried about the nature of his power and he asked the king about it. However, the answer to his question remained a mystery as King Hiryuu died.
After the death of the king, he appointed himself as the "Priest"--with the dragon crest proving his authority--and chose to stay behind when his dragon brothers left. Before the three departed, they shared a hug as Gu-En told them how they were all connected and how they will return to the heaven someday. However, Zeno at the time had come to learn about his power and thought that he could no longer return anywhere. During the time he was a priest, he solved the dangers coming to the country on his own. Twenty years later, he sensed the fleeting life of Gu-En and he became depressed as he pleaded with King Hiryuu and his dragon brothers to not leave him behind.
Unlike the three original dragons, he did not establish a village of his own. He had left the village he was born in and commented that there is not even a shadow of what was originally there. Since he was stuck in his immortal body and did not have a village he belonged to, he traveled around a lot, but after realizing that King Hiryuu may reincarnate and seeing the red dawn (the sign in the sky of the newly born reincarnation), Zeno decides that since he has waited for so long already, he might as well wait just a little longer.
-At some point in his life, Zeno was married to Kaya, a girl living on the outskirts of a certain village, she died at an early age due to an incurable disease.
-During Zeno's travels, he often got frustrated/depressed and remembers a time when he tore his body to shreds. Whenever this happened the dragon's crest always calmed him down.
Zeno is the last person to join the group. He wanders in attracted to the scent of the raw deer that Yona and Yoon were butchering. He tells Yona while praying for the butchered animal that all living things will go back to heaven and that the animal will forgive her. He introduces himself as a wandering adventurer. Due to his grumbling stomach and hunger, he is invited to have lunch with the group. The other three dragons had already suspected that Zeno is Ouryuu and he confirms that it is him. Everyone starts asking him questions, and he is asked by Kija if he feels anything when he looks at Yona, to which he simply answers that she is a cute girl, surprising the dragons who expected him to go through the awakening. He then accepts Yona's request to join the group, with others noting that he is the fastest person to join the group. Kija introduces himself to Zeno and asks him what his power is. Zeno replies that he has a sturdy body, to which Hak is quick to test by punching Zeno. He is sent flying and is visibly hurt, causing the others to question Zeno's power as Ouryuu. Despite the others' suspicions, Yona deeply believes that Zeno is Ouryuu.
Later, Zeno offers to help Yona carry the firewood, which turns out to be too heavy for him. As both of them walk, Yona claims that despite it being their first meeting, Zeno feels cheerful, different from ordinary people like a warm ray of sunshine, and just being with him brightens her mood up. She formally introduces herself and welcomes him to the group. After helping Yona, Zeno thanks the heavens and comments that the moon looks pretty.
The following day Zeno sees that Shin-Ah is shivering and proceeds to headbutt him, telling Shin-Ah that it is a way to keep warm. Shortly afterwards, Kija joins in and the three did not stop until Yoon screams at them to stop, calling them animals. At this Zeno calls Yoon a "scary boy".
The group heads to Ik-Soo's place to ask him what they should do next. Ik-Soo reveals to them that the time has not come yet for the prophecy to be set into action and the others start chattering about what to do next. Zeno interrupts and asks Yona with a serious tone about what she plans to do next since she has gathered all four dragons. He asks Yona if she plans to run away forever or if she is planning to take back the throne from Soo-won. At this, Yoon responds that it is impossible to take back the throne with the number of people the group currently has. Zeno tells them that it is possible for them to take down one castle if the four dragons use their powers seriously.  He suddenly switches to his usual cheery tone saying that he, however, doesn't have that type of power, throwing everyone off.
The group follows Yoon to Katan Village and helps him distribute rations he has brought with him. Zeno helps Kija carry the firewood and when Kija's stomach grumbles, Zeno tells him that a way to stop it from grumbling is to "firmly focus strength around your belly button". When the fire tribe officials arrive to collect taxes, Yoon tells them to hide. As the situation grew worse between the officials and the civilians, Jae-Ha gets himself involved and eventually Hak, too, gets involved. From that point on they form a bandit group call "The Dark Dragon and the Happy Hungry Bunch" which Hak and Zeno named. Hak using The Dark Dragon to refer to himself and Zeno The Happy Hungry Bunch, again, perhaps referring to himself.
The new form bandit group eventually made a name for themselves among the fire tribe people. A few days later, while Zeno was playing with the children of a village, Kija comes up to him with a disguised Kan Tae-Jun. Kija describes Tae-Jun as a sick old man and Zeno agrees to take care of him. One of the kids offers Tae-Jun a bowl of ginger soup. Tae-Jun, not pleased with the colour and smell of the ginger soup, spills it. Zeno quickly rushes over and using his hands, saves the ginger soup and puts it into a bowl. Later on, Zeno tells Tae-Jun that the ginger soup will be the first meal that the children had that day. He calls Tae-Jun "young lord", revealing that he saw through his disguise, while telling him to understand and that it was a good opportunity that he came.
Later on that day, Shin-Ah spots fire tribe soldiers marching toward the village. Zeno heads to where Hak and Yoon are to warn them about the soldiers. Upon meeting Hak and Yoon, he meets Tae-Jun and regards him as the "ginger soup guy". When Tae-Jun begs to know if Yona is alive or not, Zeno answers him and tells him that Yona is the liveliest one out of all of them which leads to Tae-Jun crying out of happiness.
Tae-Jun decides to help Yona. He commands the Fire Tribe army to go to Enri Village to make it their new headquarters. Tae-Jun and Kil-Sung try to move an old man to his house, but he would not budge. Zeno suddenly appears and juggles for the old man which made the old man happy. Zeno then offers to wash the old man and moves him somewhere else. Because of this, Tae-Jun calls Zeno amazing. Zeno tells him that is not the case and that people are like mirrors. Tae-Jun responds by saying, despite Zeno's appearance, he can say some wise things. Zeno smiles and tells Tae-Jun that he will become someone important for Kouka Kingdom. Eventually, after all matter is dealt with, Yona left the fire tribe to Tae-Jun's hand and the group heads to the Kai Empire to find a crop that will help the Fire Tribe.
The Happy Hungry Bunch arrives at Senri Village; there they disguise themselves as travelling entertainers to avoid suspicion. Yoon finds Iza seeds in the village that will help the Fire Tribe. In order to get the Iza seeds, the group performs for the villagers of Senri for the Fire Festival. As they stay at the village, they learn that soldiers from Sen are passing through their area. Zeno stays at the tent whereas the others went outside to inspect.
The group decides to go to Saika, the Fire Tribe's capital. There they gather information. They stay at a tavern where they receive words that the Sen army has already invaded Kouka and is advancing towards Saika. Yona decides to stop the army. Through the secret passage that Zeno found out, they casually walk into the enemy's encampment and attack them. Shin-Ah notices another army but notes that they are not heading toward Saika but to Hiryuu Castle. Hak eventually comes to the conclusion that the Fire tribe and the Sen are cooperating together to kill Soo-Won.
They head toward Hiryuu castle to stop the army. They engage in a battle but leaves when Soo-Won shows up. Afterwards, Yoon heals the injuries that they got from the battle. Jae-Ha states that he is surprised at how little injuries Zeno and Hak got. In response, Zeno says that he was just cheering everyone on to which Kija scolds him and tells him to act a bit more like a dragon. Yoon defends Zeno saying that he protected him and Yona who couldn't fight. Zeno blushes and thanks Yoon.
The group goes to Shisen, a port town in the Water Tribe. After Jae-Ha fell sick from drinking Nadai, a type of drug, the group heads to the place where he had fainted to investigate. Zeno finds a dead body floating in the water and tells Yona about it.
The Happy Hungry Bunch once again became entertainers for a bar to gather information about the drug. An Lili, the daughter of the head of the Water Tribe gets attacked by the Nadai users in the bar. When one of them chased after her, Zeno jumps on top of the person and tells her to run away. The Nadai user throws Zeno off, slamming him into a table.
After rescuing Lili, the group plans to go to Suirei, the shop that fed Jae-Ha the Nadai. They left Zeno, Yoon, Shin-Ah and Yona out of the plan. The next day, while the plan was being executed, Zeno, Yoon, Shin-Ah and Yona stays at the inn where Lili is staying at. When Yona is attacked by Hiyou, Zeno shields her. After Hiyou runs away, Shin-Ah tries to chase him but Zeno stops Shin-Ah, saying that they need to treat Tetora and Yona first. He volunteers to apply the medicine for Yona the day after.
The group finds out that Hiyou has another headquarter in a town call Sensui. They separate from Lili and head toward that town.
A few days later, the group obtains information that Nadai can be bought from a store call Utsuro. As they were heading to the Utsuro, Shin-Ah suddenly walks toward the sea instead. Zeno and Hak follow him and find a ship heading toward Sensui. After figuring out that the ships are merchant ships from Southern Kai, Hak instructs Zeno to tell Yona about it. Zeno approaches Yona to warn her and meets Soo-Won. He stands there briefly, staring at Soo-Won until Yoon asks him what he came to say. Zeno tells them about the incoming merchant ships and Soo-Won suggests to ask the townspeople to lend them a few ships to confront the merchant ships. Yona decides to stay with Lili who is with Soo-Won. Kija protests against the decision and wants to stay with Yona. Zeno volunteers to stay with Yona and swears upon the name of Ouryuu to protect her.
Later on, Zeno offers to piggyback ride Yona because of her back injury. Lili asks Soo-Won to guard Yona since Soo-Won is Lili's bodyguard at that time. While Yona tells Lili that she is fine, Zeno senses an arrow aiming at Yona and shields her. Soo-Won shields Zeno and Joo-Doh shields Soo-Won. Yona tries to shoot one of Hiyou's men down but is stopped by Soo-Won who tells her to stop moving around carelessly. Zeno agrees with Soo-Won. He pats Yona on the head telling Yona that she isn't calm when Soo-Won is around. He explains to her why Soo-Won stopped her from shooting the arrow and says that he will help her since she is smart. Hiyou suddenly appears and tries to stab Yona. Zeno quickly shields her to protect her but Hak interferes and protects the two of them.
After taking care of the Nadai situation, the group and Lili eat dinner together before the group's departure. During the dinner, it starts raining so they move to a tent to eat.
On the day that the five tribes decide to advance toward Kai Empire and reclaim Kouka's northwest region, Zeno is shown looking at the sky before he joins Yona and the others.
The Happy Hungry Bunch arrives at a village along the border of the Earth Tribe. In the village, Yona's rice ball gets stolen by a boy name Kalgan. They escort Kalgan to his village which is in the Kai Empire. Once they enter Kalgan's village, the dragons fall sick one by one. The only dragon that did not fall sick is Zeno. He decides to take care of them and reassures Yona and the others that he won't get sick saying that health is one of his only strong points.
In the tent where the other dragons are resting, Jae-Ha complains about how there were no cute girls visiting them. Zeno offers to cross-dress for him but Jae-Ha refuses. Zeno explains to the other dragons that they are sick because they are away from Hiryuu castle. He informs them that the dragons are more prone to sickness and fatigue when they are away from the castle since the castle is a place where the divine protection for the dragon is strong. Kija asks Zeno if Ouryuu village teaches him stuff like that. He replies by saying kind of. He tucks Kija into bed and Kija states that he looks nostalgic. As the dragons slowly fell asleep Zeno promises to protect them. He exits the tent and senses that something was wrong.
It turns out after Kouka won the war against the Kai Empire, the Kai Empire army decides to burn down the villages they have to give to Kouka. One of the villages is Kalgan's village. Kalgan is chase by one of the Kai Empire soldiers when he visits another village to buy medicine for the sick dragons. Yona instructs Zeno to take Kalgan back to his village and warn the other villagers.
The sick dragons get up from their bed to fight along with Hak to repel the Kai soldiers. But because of their sickness, they get injured and could not stop the Kai soldier from advancing toward Kalgan's village. Yona tries to stop the soldiers but was told by Zeno to stand back. Zeno runs toward one of the soldiers and is sliced. He falls down but quickly stands up again and tries to stop another soldier. Zeno gets stabbed and thrown aside. The Kai soldiers advance toward Yona. Yona, crying, clings on to Zeno's body and says that she won't forgive the soldiers. In response, the soldiers start to laugh. Zeno suddenly reaches up to touch Yona's cheeks and tells her not to cry. He gets up; his sleeve falls down and his wound is shown healing. He notes that he is healing slowly since he is away from Hiryuu Castle. He reassures Yona that he won't die and tells her that he is the dragon that is born as her shield.
The soldiers look at him in disbelief. One of them stabs Zeno in the heart and he collapses into Yona's arms. The wound on his chests heals immediately as he stands up. The soldier screams and slices off his right arm. Zeno asks Yona to lend him her blade as the soldier slices off his other arm. One of Zeno's arm grabs Yona's dagger and stabs the soldier from behind before reconnecting back to his body. He asks the soldiers to please go back home. As a response, the soldier screams at his comrades to kill the "monster". Zeno smiles at Yona before charging at the incoming soldiers. As he charges at a soldier, his other arm reconnects back to his body. One of them slices his jaw, cutting the medallion he has hanging on his head. His jaw heals right away.
Multiple swords pierce through his body. Another soldier chops off his head as an attempt to kill him. But all attempts were in vain as his head reconnects back to his body and his wounds close. Zeno charges at a soldier again as the soldier screams and swings his sword at Zeno but it wouldn't slice through. Zeno tells him that he can't pierce him anymore as his face starts forming dragon scales. He easily defeats the soldier with only one hand. Another soldier also swings a sword at him. He grabs it and shatters the blade before kicking him. Zeno leaps, flying and crushes another soldier that was on a horse. The Happy Hungry Bunch stares at Zeno in shock at his abilities as the Ouryuu. He cheerfully asks them if they're alright and explains to them how his abilities work. He tells the soldiers that he has no limits and can go fighting for hundreds of years. He finishes his speech by telling them to come at him, that he has all the time in the world. The soldiers run away retreating. Zeno picks up his medallion that fell when he was fighting. Yona and the others run toward him and hug him. Zeno at first was surprised but later on, reassured them that he is okay and tells them that they are all adorable with a smile.
The group leaves the village and goes back to Kouka. When Jae-Ha was trying to see Shin-Ah's eyes, Zeno remarks about how lively the group is despite their injuries. Yoon and Jae-Ha approach Zeno and pull his sleeves up. Yoon comments about how there is no more scales on his arm and Zeno tells him that after some time passes, his skin returns back to normal skin. Yoon then asks him how old he is and Zeno answers that he is seventeen years old. To this response, everyone calls him a liar and asks for his real age. He reveals that he does not know the exact year because counting is a pain. Kija asks him if he is one of the first generation dragons. Zeno answers that he is, in fact, the first dragon that served under King Hiryuu. He tells them that he could once hear the voice of the gods, that he was given an immortal body, and that he was married once. He announces to Yona that he was waiting for her, informing her that she is the reincarnation of King Hiryuu. When Kija asks him why he did not appear as soon as Yona needed the powers of the dragons, Zeno says that he was testing her, to see if she is worthy of the power of the dragons and that in the end, he decided to follow her. Yona tells him that she does not have any special powers. Zeno reassures her that King Hiryuu was also just human and that she does not need to follow Hiryuu's footstep. After that, he asks if there was any more questions and concludes that they are done. Hak asks him why he stayed quiet about his powers. To this Zeno says that nothing will change whether they know about it or not since his powers only activate when he gets injured.
Later that night Kija helps Zeno carry the bed sheets. Kija reveals to Zeno that he always wanted to meet the first generation dragons. He tells Zeno that if he went to Hakuryuu village, they and their ancestors would have welcomed him. Kija then considers what the other dragons have gone through and calls himself blessed. Zeno starts laughing and says that Kija is amazing. He informs Kija that the previous Hakuryuus have longed for the king too much that they sort of became evil spirits. They cling on to every single new Hakuryuu but Kija embraces and accepts them. Zeno tells Kija that he reminds him of the first Hakuryuu and pats him on the head before going to sleep. On the bed, he suddenly remembers the day when he drank the dragon's blood. Zeno quickly falls asleep and dreams of his past. He remembers the times when he visited the current dragons when they were still children. He wakes up to find the current dragons and Yona looking at him, waiting for him to wake up. Zeno beckons them to come forward and pulls them into a hug. He comments to himself about how much they have grown now.
Immortality: As the possessor of Ouryuu’s power, Zeno has an infinite lifespan. Due to this, he has stopped ageing, giving him the same appearance as when he drank the dragon’s blood two thousand years ago, and can’t get sick even if he is away from the Hiryuu Castle, unlike the other three dragon warriors.
- Regeneration: Zeno can regenerate quickly from the injuries he receives, which cause the dragon scales to form on his body after he heals. Depending on where the dragon scales form, these parts of the body cannot be hurt any further once they regenerate. This explains why Zeno did not appear to have an indestructible body and could be easily hurt like a normal human in the beginning, as it was necessary for him to be hurt deeply on certain areas of his body. Furthermore, even if a part of him is cut off, Zeno can still control it at will and reconnect it back to his body. However, after a while, the injured parts of him that turn into dragon scales return to its normal human form. Even though he doesn't get sick from being far away to the Hiryuu Castle, his regeneration slows down.
Melee Combatant: Despite looking like a person who doesn't train his body, Zeno can handle fights against numerous soldiers, armed or unarmed. This is further enhanced if Zeno gains the dragon's scales on his arms and feet which gives him immense strength similar to Kija's dragon claw and Jae-Ha's dragon foot. He mentioned in a later chapter that he once gouged out his eyeballs (probably in an attempt to test if his eyesight would improve to Shin-Ah's level), but all that did was make his eyes "super strong". Nevertheless, he mentions that he has always had good vision.
Other: Just like the other dragon warriors, Zeno's soul seems to be able to protect Yona in desperate situations, when he and the others can't.
When Zeno first met Yona, he did not receive the initiation like the other three dragons. It is later on revealed that he is the first generation Ouryuu, thus he wouldn't receive the initiation due to his previous loyalty to King Hiryuu. Throughout the series, he's also seen to not pay any special attention to Yona, while the others did. He treats her just like a normal comrade of his and never called her by her name, usually by 'Miss'. However, he seems to find Yona extremely cute and tends to protect her a lot when they are on the battlefield or in danger.
Later on, it is revealed by Zeno himself that he has been following Yona around ever since she left the castle. He knows that Yona is the reincarnation of King Hiryuu and has been watching her gather the dragons and overcoming obstacles. He stated it was because he wanted to know if Yona was capable/worthy of using the power of the four dragons. After watching her leave Awa, he thought it was alright to entrust himself to Yona like he did for King Hiryuu and went out to meet them after that.
Like with the others, Zeno also treats Hak as a fellow companion. Zeno considers Hak as a man who's incredibly strong, claiming that his power is not normal for a human. He also seems to worry for Hak when he warns Hak that his lifespan might decrease if he kept worrying about the princess and puts his own life on the line just for Yona. He assures him that as long as the four dragons are around, he need not worry about Yona, as nobody can replace him if he dies.
Zeno first joined the group because of Yoon's superb cooking; according to him, he's "attracted by the smell of tasty food". Later this was revealed to be an excuse he used to meet Yona without rest of them getting suspicious. He also claims Yoon to be a rather scary boy and later starts to respect him. He also shows concern for Yoon and has the habit of calling him "kid" (sometimes also translated as "lad").
Shin-Ah is probably the closest to Zeno aside from all other dragons as they are always seen together (mostly because Zeno loves to snuggle in Shin-Ah's fluff) and Shin-Ah seems to feel calm around Zeno. Like the rest of the group, Zeno is heavily protective of him and seems to show a subtle older-sibling-like fondness for him. He continues his habit of nicknaming all of his companions with Shin-Ah, as he only ever refers to him as 'Seiryuu'.
Zeno knew Tae-Jun's identity right when he first met him despite his disguise which worried Tae-Jun for a while. Tae-Jun said that Zeno, despite his looks, could actually spout some really wise things. Later on, Zeno predicted that Tae-Jun will be a really important person to the Fire Tribe and is seemingly surprised when Tae-Jun reveals that he does not desire to be somebody important for the tribe.
Being sworn to protect Hiryuu through Zeno's dragon's blood, Zeno respects King Hiryuu deeply and calls him "Lord Hiryuu". To him, Hiryuu was the one who brought all the dragons together and made them feel actually connected to each other whenever he was around.
When Hiryuu found out about Zeno's powers, he seemed upset and gave him his pendant as proof that he will be with Zeno, even when everyone is gone. He treasures the pendant that Hiryuu gave him a lot, so much so he was afraid that Kaya had accidentally thrown it away when she's cleaning his wounds and even in the present, he still picks it up from the ground after it was cut off.
Zeno saw Guen as a wild boar that acts recklessly and deeply regrets not visiting the Hakuryuu village after they were all separated, even though Guen said that he'll wait for the day Zeno comes to visit him even if he's an old man then. Thus, when Zeno realized that Guen had passed away, he was extremely upset and screamed, begging King Hiryuu, and his dragon brothers not to leave him alone.
Zeno also remarked that Guen and Kija are similar to each other.
He viewed Abi as one of his dragon brothers and was very upset when Abi passed away. He was also the one who protected Abi on the battlefield when his dragon eyes backfired on him and he was paralyzed.
He viewed Shu-Ten as one of his dragon brothers and a guy who is strong and reliable even though the latter doesn't seem to recognize Zeno as a dragon warrior. Zeno was very upset when Shu-Ten passed away.
Kaya was Zeno's wife.
Zeno first meets Kaya when she rescues him from the snow and cleans him up. Later Kaya tells Zeno that she has an incurable disease, which is why she lives secluded from people to prevent them from getting infected as well. He then offers to take care of her for a period of time until she recovers as a favor to her for rescuing him.
Zeno slowly falls in love with Kaya as they continue to live together. However, Kaya's condition gets worse and she couldn't leave her bed because she was too ill, so she asks Zeno to leave before he gets infected as well. However, Zeno reminds her that he won't get sick and carries on to propose to her which touches Kaya and she cried tears of joy. Unfortunately, in the end, Kaya couldn't make it through and dies holding Zeno's hands. Her last words to him were "May we meet in Heaven again", to which the latter nods gently, upset. He stays with her until she is no longer a corpse but a skeleton, hinting that he wouldn't leave her even after her death.
Even after her death, Kaya's impact on Zeno is great. She helped him heal from the death of the other dragons and even taught him to speak in the third-person speech to prevent himself from forgetting his name, to which he later laughed and commented, "I feel just like a kid." She was also why he started to treasure food and the people around him, as living with her made him realize how hard life could be and made him more appreciative. Putting his hands up in the air when he's happy is also a tic he copied from her. He even wears a scarf in a similar fashion to how she wore her's. Even when he told the dragons he was once married with a very casual, light-hearted tone, Zeno misses her greatly as she had a big role in his life.
- (To Yona) "Well miss, that's splendid. But everything that lives, will return to heaven one day."
- (To Tae-Jun) "People are mirrors. If you smile a smile will be reflected."
- (To Hak) "Even if we dragons die once, we will be replaced someday. But no one can replace you, big brother, so you must treasure yourself."
- "I might be the odd picking of the dragons, but I'll make sure that I'll protect all of you with all my might."
- (To Yona) "I am the dragon that was born to be your shield. If Ouryuu, your shield, protects you...You will never...be injured."
- “No matter how many times you tear me apart...I will be everyone's shield.” 
- (To enemy soldiers) “What will you do? Unlike you, I have no limits. I can go on fighting for hundreds of years. Come at me, I have all the time in the world."
- (To Jae-Ha) "Stop talking about my age already."
- (To Happy Hungry Bunch) "Are there more questions? Are we satisfied? Then we're done, we're done."
- He ranked 8th in the character popularity poll conducted by Hana to Yume in December 2014. He scored 439 in total.
- Zeno seems to dislike getting teased for his age.
- In earlier chapters, Zeno's eye color was brown; however, in later chapters, it has been recolored to blue.
- Amongst the four dragons, he and Jae-Ha are the only known dragons who were known to be able to see the spirits of dead people.
- After the fact that he is capable of cooking was discovered by Yoon, he became the second chef of the group.
- In the past, Zeno has already gouged his eyes out but all that happened was they became "super-strong", but according to himself, his eyes were good, to begin with.
- It has been shown that Zeno can never lose the crest Hiryuu gave him. When he gave it away, it magically returned to him.
- Zeno is the one that adds "The Happy Hungry Bunch" to the name "The Dark Dragon and the Happy Hungry Bunch".
- According to Zeno, he can ride a horse while standing up.