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) has been confirmed by Jae-Ha and Kija to be the current 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 an extremely happy person. He has blue eyes (previously brown) and thick, messy yellow hair. He puts a short green bandanna with an orange hanging beaded accessory decorated with a gold circular dragon design around his forehead and ties it in a bow on the right side.
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 turns to steel and has a scaly yellow look.
Zeno is an energetic, cheerful young man who enjoys the company of others. He mostly uses third-person speech and probably never called anybody by their name even after learning their name. (He calls the dragons by their names, ex: Seiryuu or Ryokuryuu) Most of the time, he appears to be childish and an attention-seeker, though he can be wise and mature when he wants to. 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 how he found the group so quickly in the middle of a forest. 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 aging 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 were leaving. 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 their 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, where he wandered in when he smelled the scent of raw food (deer). He then told Yona while praying for the butchered animal that all living things will go back to heaven and that the animal will forgive her. He introduced himself as a wondering adventurer. Due to his grumbling stomach and hunger, he was invited to have lunch with the group.The other three dragons had already suspected Zeno is Ouryuu and he confirms that it is him. Everyone starts asking him questions, and 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 accepted Yona's request to join the group, with others noting that he was 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 wood, which turns out to be too heavy for him. As both of them keep walking, Yona claims that despite their first meeting, Zeno feels cheerful, different from ordinary people like a warm ray of sunshine, and just being by him, her mood brightens up. She formally introduces herself and welcomes him to the group. After helping Yona, he thanks the heavens and comments that the moon looks pretty.
Many chapters later, Zeno remembers the times when he visited the current dragons when they were still children. He comments to himself how much they have grown as Zeno looked at them, all grown up and travelling with Yona.
Immortality: As the possessor of Ouryuu’s power, Zeno has an infinite life span. Due to this, he has stopped aging –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 dragons warriors.
- Regeneration: Zeno can regenerate quickly from the injuries he receive, 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 can 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 Sin-Ah's level), but all that did was make his eyes stronger. Nevertheless, he mentions that he has always had good vision.
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 seem 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.
One of the main reasons Zeno joined the group is most probably due to Yoon's cooking as he's attracted by the smell of tasty food when he met them, and was then revealed to be an excuse he use 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.
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.
Zeno respects King Hiryuu deeply because of the dragon blood 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 Gu-En as a wild boar that acts recklessly and deeply regrets not visiting the Hakuryuu village even once after they were all separated, even though Gu-En said that he'll wait for the day Zeno comes to visit him(even if he's an old man then), he never did. Thus, when Zeno realized that Gu-En 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 Gu-En 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 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 met Kaya when she rescued him from the snow and cleaned him up. Later it is revealed to Zeno that Kaya has an incurable disease which is why she lives secluded from people, to prevent people from getting infected by her disease. He then offers to take care of her for a period of time until she recovered as a favor to her for rescuing him.
Zeno slowly fell in love with Kaya as they continued to live together. However, Kaya's condition got worse and she couldn't leave her bed because she was too ill, so she asked Zeno to leave before he got infected as well. However, Zeno reminded her that he won't get sick and carries on to propose to her which touched Kaya and she cried tears of joy. Unfortunately, in the end Kaya couldn't make it through and died holding Zeno's hands. Her last words to him were "May we meet in Heaven again." which the latter nods gently, upset. It is later shown that he stayed with her till she was no longer a corpse but a skeleton, hinting he wouldn't leave her even after her death.
Even after her death, Kaya's impact on Zeno is great. She made him a more casual and lively man and even taught him to speak in third-person speech to prevent himself from forgetting his name which the latter 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 light-hearted tone, it seems that Zeno himself still 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."
- He ranked 8th in the character popularity poll conducted by Hana to Yume in December, 2014. He scored 439 in total.
- Apparently, 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.