Ayumi Tōgeguchi, a first-year in Class 1-3 at Roubai Girls’ Academy (seat 10), wears her hair in twin tails and maintains a quiet presence, deliberately minimizing speech to conceal her regional accent. This self-imposed silence strains her interactions, though sparks of emotion occasionally break through her restraint. Struggling with severe anxiety, she relies on daily medication facilitated by a peer, underscoring her dependence on external support. She shares a dorm room with Minoru Ohkuma, a classmate whose antisocial tendencies mask a sharp curiosity for observing others.

Ayumi’s name intertwines symbolism: “Ayumi” fuses “freshwater trout” (鮎) and “beauty” (美), while “Tōgeguchi” (峠口) evokes a mountain pass’s threshold. Though she belongs to the table tennis club, her participation remains undefined, leaving her pursuits as quietly enigmatic as her guarded demeanor.