Yuuta serves as the central protagonist, a 16-year-old with brown hair and brown eyes from an ordinary Japanese family. A benefactor, recognizing his interest in art, secures his enrollment at the exclusive all-male St. Alphonso Academy on a remote Pacific island. His modest background starkly contrasts with the aristocratic and celebrity-connected students, positioning him as an audience surrogate within the opulent environment. Yuuta maintains a consistently kind, caring, determined, and optimistic disposition, approaching new experiences cheerfully.

His arrival triggers immediate challenges, including a false theft accusation in Episode 1 stemming from his newcomer status, straining initial peer relationships. Student council president Joshua intervenes to resolve this conflict and later prevents Yuuta's expulsion over a documentation error. Yuuta's routine includes video calls with his unnamed older sister; these conversations reinforce his strong family bonds and serve as a narrative conduit for introducing other characters and their backstories, bridging the isolated academy and the outside world.

Yuuta forms significant relationships: his kindness softens Alfred's brashness, he shares a deep bond with Joshua (who gifts him a bunny charm that later deflects a fatal stab), and maintains positive dynamics with peers like Henri and Sylvain. His open-hearted nature connects him to students grappling with hidden traumas, though his own personal history beyond his family remains largely unexplored.

Throughout the series, Yuuta evolves from an overwhelmed transfer student into a supportive figure who positively influences others. His presence catalyzes emotional breakthroughs for fellow students, often expressed through musical sequences depicting their internal conflicts. While the narrative focuses on his interactions and their developmental impacts, Yuuta's individual story lacks extensive backstory or resolution, concluding without definitive closure for his journey.