Ryunosuke Yoshioka (龍之介 吉岡) is a first-year student in Class 1-3 at Kuromata High School, a track team athlete, a manga fan who is familiar with the "Dragon Son bloodline" trope, and the person who ran two legs of an obstacle course relay in a wedding dress to defend Ruri Aoki's honour. He is 15 years old, 172 cm tall, blood type AB, and his birthday is July 21st.
He sits directly in front of Ruri in class and has attempted to chat with her since before the horns appeared. Ruri originally labelled him a "serial small talker" and found his constant conversation attempts difficult to manage. He continued anyway. He was the first student to greet her with normalcy when she returned to school with horns — noting her shorter hair, treating the return as an ordinary day, moving on.
His most significant contributions to Ruri's arc: refusing to introduce Homura Kagami to Ruri at the Sports Festival because he did not want to sell out a friend; running the relay in absurd conditions in a wedding dress and losing by a narrow margin; and then, in Chapter 40, yelling at Ruri in a school hallway that all of this revolves around her and she has to take some kind of stance. That last one was the catalyst that made Ruri decide for herself to stay in human society. He immediately pledged to have her back.
Yoshioka is a teenage boy standing at 172 cm with short, somewhat spiky dark hair that he has been growing out since the start of the school year — a gradual change the author tracks across chapters. He has dark eyes and a frequently determined or neutral expression. The author noted he is a "good reminder of how much I enjoy drawing guys."
He is typically seen in the Kuromata High School uniform: white long-sleeved shirt, dark necktie with white polka dots, light-coloured trousers. During the Sports Festival he wore the class-branded black "Dragon" t-shirt. For the final anchor leg of the obstacle course relay, he was required to wear a large white wedding dress — an obstacle race condition that earned him the nickname "The Burliest Bride" from classmates.
Yoshioka is direct, sociable, loyal, and enthusiastic about dragons in the specific way of a person who grew up reading manga and immediately recognised Ruri as a "Dragon Son bloodline" trope made real. He thinks this is genuinely cool. He is not performing enthusiasm. He is a teenage boy who likes dragons and now sits in front of one.
The Serial Small Talker
He initiates conversation as a baseline behaviour. He tried to chat with Ruri before the horns appeared, while she was in social-anxiety mode, through a personality style she found exhausting. He continued anyway because the conversation attempts were not about managing her — they were just him being himself at the person in front of him. When the horns appeared and most classmates recalibrated their approach, Yoshioka did not. He greeted her. He noted her shorter hair. He moved on.
Integrity About Friendship
When Homura Kagami insulted Ruri and demanded an introduction, Yoshioka's response was immediate and specific: "Sell out a friend... is the last thing I wanna do." He did not deliberate. He ran the relay in a wedding dress to back that position up physically. He lost the race. He did not consider this a complication of his original position. He later revealed he felt a sense of personal responsibility for Ruri because he had been on the receiving end of the fireball early on — which is the most Yoshioka possible reason to feel responsible for someone.
The Straight Talk
His defining contribution to Ruri's arc was telling her, at volume, that everything revolves around her and she has to take a stance. He acknowledged being harsh about it. He did not walk it back. He followed it immediately with a pledge of loyalty and "Cuz boys love dragons, and nothing can change that." Both parts — the demand and the declaration — are him at full sincerity simultaneously.
Personal Details
He has a secret frustration that his younger sister has begun to resemble him. He enjoys manga. He considers himself "kinda smart" and his peers agree. He was quick to shut down Sakuraba's suggestion that he had romantic feelings for Ruri: "Don't go making everything about romance."
The Direct Classmate — Chapters 3–14
Yoshioka had been trying to chat with Ruri since before the horns. When she returned from the fire-breathing medical absence with shorter hair and visible anxiety, he greeted her as if the week had been ordinary. He asked her what a dragon even was in Chapter 14, attempted to trade touching her horns for letting her touch his hair, and treated her draconic biology with the same casual curiosity he had applied to her before it was publicly apparent. This normalising consistency was Ruri's first successful human interaction post-transformation and functioned as evidence that her classmates could treat her as a person rather than an anomaly to be managed.
The Sports Festival Duel — Chapters 26–28
Selected to run both the first and anchor legs of the Obstacle Course Relay, Yoshioka encountered Homura Kagami from Class 2, who made derogatory comments about Ruri ("monster girl," "giant forehead") and demanded Yoshioka introduce him to her. Yoshioka refused: "Aoki's a friend, so I can't let you win this." He converted the race into a personal duel.
The obstacles: dragging a heavy tire, riding a tricycle, and running the anchor leg in a large white wedding dress. He was described as a "muscle monster" for the tire section. He earned the nickname "The Burliest Bride" for the final section. He lost the race by a narrow margin to Kagami. He did not sell out his friend. He told Kagami the only relevant information: Aoki was a friend. The loss was narrow. The position was unchanged.
The Hallway Confrontation — Chapter 40
During the class ground rules meeting about Ruri's dangerous Frost trait, Yoshioka admitted to Umi Aoki that he had initially thought Ruri leaving school might be "prolly for the best." In a private hallway confrontation afterward, he told Ruri directly what he thought was actually happening: "All of this revolves around you!! You have to take some sort of stance!" He called out her people-pleasing as a failure to take responsibility for her own presence in her own life.
This was the moment that forced Ruri to make a choice rather than let the situation make it for her. She decided to stay. Yoshioka pledged: "I'm on your side. The choice really is up to you... and I've got your back." He closed with: "Cuz boys love dragons, and nothing can change that." Both of these statements are sincere and they are both characteristically him.
Ruri Aoki — From Nuisance to Champion
Ruri considered him a nuisance before the horns appeared. He was the first person to greet her normally after they did. He ran a relay in a wedding dress to defend her reputation. He yelled at her in a school hallway until she decided for herself to stay in human society. He immediately pledged to have her back regardless of her choice. The trajectory from "serial small talker Ruri couldn't deal with" to "one of her most trusted human champions" is direct and earned through specific acts at specific moments. He later revealed he felt personal responsibility for her because he had been hit by the fireball. This is the most Yoshioka possible origin for a protective instinct.
Homura Kagami — Rival and Foil
Kagami from Class 2 insulted Ruri and demanded an introduction. Yoshioka refused the introduction and turned the relay into a duel. He lost the race. He did not introduce Kagami to Ruri. His position on not selling out his friend was maintained through the loss. Kagami is the character who exists to demonstrate what Yoshioka will and will not do under competitive pressure. The answer: will run in a wedding dress, will not change his mind about Ruri.
Umi Aoki — Consulted Adult
Umi consulted with Yoshioka after Ruri's first fire-breathing incident to help manage the classroom atmosphere — which suggests she identified him early as a reliable class presence who could be useful for Ruri's social reintegration. He also told Umi directly, during the ground rules meeting, that he had initially thought Ruri leaving might be for the best. Umi is apparently one of the few adults he speaks to about Ruri's situation with full honesty.
Sakuraba — Classmate Who Noticed
Sakuraba suggested Yoshioka had romantic feelings for Ruri, to which he responded clearly: "Don't go making everything about romance." She describes him as "a romantic at heart" for how much he cares about Ruri's status in the class. He disagrees with the framing. Both readings are present in the text and neither is definitively resolved.
- Yoshioka's birthday is July 21st, his blood type is AB, and he stands at 172 cm. His given name, Ryunosuke, contains the kanji for "dragon" (龍 / Ryū) — which the series acknowledges as a thematic connection to Ruri and which he is apparently aware of and pleased about.
- He is the only student in Class 1-3 to run two separate legs of the obstacle course relay — the first and the anchor — in the same race. He ran the anchor leg in a large white wedding dress. He earned the nickname "The Burliest Bride." He lost. He did not change his position on Ruri.
- He enjoys manga and is specifically familiar with the "Dragon Son bloodline" trope — the narrative convention where a protagonist has legendary dragon heritage that grants exceptional power. He applied this frame to Ruri immediately and has found her situation genuinely exciting partly because of it. His enthusiasm for Ruri's biology is grounded in a specific cultural reference that makes the enthusiasm feel like his own.
- He revealed to Sakuraba that he felt personal responsibility for Ruri because he was "on the business end of that fireball" early on. He did not want to see her face major consequences for a biological accident that also happened to him. This is an unusually direct and specific origin for a protective instinct: he was there, he got hit, and he decided that what happened to her mattered because of that.
- Author Masaoki Shindo noted that Yoshioka is a "good reminder of how much I enjoy drawing guys" and that his hair is visibly growing out as the story progresses. The growing hair is tracked across chapters as a small continuity detail. He started the year with shorter hair. It is getting longer.
- His secret frustration is that his younger sister has begun to resemble him. This is a completely ordinary sibling concern presented as a character detail in a manga about dragons. It functions as exactly the kind of mundane, human personal problem that makes him feel like a real person alongside all the obstacle-course wedding-dress loyalty content.