Leader of the yakuza group Kuryugumi at just 14 years old following his father's assassination, Ryuuji appears significantly older than his age due to his towering height and perpetually stoic expression. Despite showing no outward signs of sorrow or tears after his father’s death, he seizes the chance when Tsukasa claims she can identify the murderer, who also killed her parents. Unbeknownst to her, Ryuuji already knows Tsukasa’s secret—that she is actually a girl—much to her astonishment. He has harbored a long-standing interest in her without her knowledge, envying her effortless smile and captivating charm.
Upon seeing Tsukasa dressed in girls' clothing for the first time, truly acknowledging her as a girl, Ryuuji concocts a "debt" based on her brothers’ food consumption, coercing her into staying on as his bodyguard to repay it. He continuously inflates this debt by charging for every meal Tsukasa eats, any damage she causes, and any bill remotely connected to her—all in an effort to keep her by his side for as long as possible. Additionally, he openly flirts with her, though she remains oblivious to his true intentions, being rather naive in such matters.
