Ayumi Togeguchi, a first-year student in Roubai Academy’s Class 1-3 (seat 10), navigates her new life as a transplant from Aomori Prefecture, her self-consciousness about her rural dialect often silencing her in class—except when strong emotions loosen her restraint. Her given name merges "freshwater trout" (鮎) and "beauty" (美), echoing ties to nature and elegance, while her surname, Togeguchi (峠口)—"pass" and "mouth"—hints at thresholds and gateways.

Residing in the Full Moon Dormitory with roommate Minoru Ohkuma, Ayumi channels her athleticism into the table tennis club, earning recognition by reaching a district tournament semifinal as a rookie. Her spirited determination shines during school events, from leading cheer routines at sports festivals to collaborating fiercely in team competitions.

Cheerful yet privately insecure, Ayumi measures herself against peers like Erika Kizaki and Riri Minakami, grappling with envy when witnessing Komichi Akebi’s closeness to Erika. Her tentative steps toward friendship begin during the entrance exam, where she offers Komichi a handkerchief—a gesture reciprocated when Ayumi returns it at the entrance ceremony, cementing their supportive bond.

Anxiety shadows her resolve, requiring medication discreetly managed with Komichi’s aid, reflecting their deepening trust. Her affectionate nature surfaces in frequent embraces with close friend Hotaru Hiraiwa, balancing vulnerability with earnest effort to connect. As a rural student adapting to dorm life, Ayumi treads the line between lingering self-doubt and her yearning to belong, quietly bridging the gap between her roots and newfound community.