Sugiyama-senpai, an upperclassman mistakenly credited by the protagonist as her rescuer after she collapsed at a train station due to anemia. This misconception fuels her belief in a fated bond, sparking intense romantic pursuit. However, Sugiyama-senpai finds her relentless advances overwhelming, rejecting her with the frank assessment that her attentions feel "heavy." His rejection prompts her emotional withdrawal.

As the protagonist shifts focus to managing the boys’ basketball team, Sugiyama-senpai’s presence diminishes. Her subsequent discovery that another student, Aki Hidaka, actually aided her during the incident solidifies Sugiyama-senpai’s narrative role as a transient romantic catalyst, redirecting her affections toward another.

Across all official media—including manga, anime, and spin-offs—Sugiyama-senpai’s background, motivations, and personal history remain unexplored. His characterization is strictly confined to instigating and concluding this pivotal narrative shift, with no elaboration on his existence beyond these events.