Kou Suzuya is a charismatic and flamboyant upperclassman in Boku no Hatsukoi o Kimi ni Sasagu, where he serves as the dormitory leader and is widely admired by his peers, who affectionately call him Kou-sama. His personality is outwardly confident and attention-seeking, marked by a habit of openly flirting with Mayu Taneda and provocatively inserting himself into her relationship with Takuma Kakinouchi. Beneath this playful arrogance lies a deeper motivation rooted in personal loss. Kou's father died of the same incurable heart condition that threatens Takuma, an experience that left him deeply skeptical of love tied to impending death and determined to protect Mayu from what he sees as inevitable heartbreak. For much of the story, he actively opposes the couple's bond, challenging Takuma directly and even asking him to relinquish Mayu, while his own feelings for her gradually shift from a competitive game to genuine affection. His involvement intensifies when he agrees to a hundred-meter race with Takuma to decide who will step aside, a contest he loses. In a tragic turn, Kou is struck by a train and rendered brain-dead shortly afterward. Because he had previously registered as an organ donor, he becomes a potential heart donor for Takuma. This twist transforms his role from a persistent rival into a central figure in the story's moral and emotional climax, forcing those around him to grapple with the weight of his legacy, the meaning of his death, and the possibility of saving Takuma at the cost of acknowledging Kou's own latent goodwill. Though his family initially refuses to consent, the presence of tears on his still face and his documented donor status suggest an unspoken wish to do something meaningful. Ultimately, Takuma chooses not to accept the transplant, but Kou's accident and its aftermath irrevocably alter the lives of everyone involved. As the saga unfolds, Kou matures from a self-assured provocateur into a more reflective young man, his arc shaped by vulnerability, thwarted love, and a tragic end that underscores the themes of sacrifice and interconnected fates.