Toko emerges as a central figure within the group of six teenage girls whose sea vacation transforms into a desperate struggle for survival. Her background of privilege is marked by the yacht, belonging to her father, that facilitates their outing—positioning her as the initiator of the fateful sea trip.

When armed fugitives seize the vessel, Toko demonstrates early leadership, coordinating the girls' resistance against their captors amidst a violent storm to regain control. Following the yacht's wreck on a deserted island, her protective instincts and resourcefulness persist as she participates in evading the criminals and organizing the group's survival.

This commitment drives her to intervene directly, rescuing Ayaka from restraint and assault by Kaneda. This act, however, results in Toko and Natsuno being captured at gunpoint and coerced into performing sexual acts on each other. These shared traumatic experiences leave profound psychological wounds described as "sexual marks of violence latched on their body and soul," severely damaging trust and cohesion within the group.

The cumulative trauma and relentless threat environment trigger intense psychological strain across the group, manifesting as heightened fear, loneliness, and eroded mutual trust. Toko specifically confronts confusing and involuntary emotional responses during enforced intimacy, indicating complex psychological adaptation under extreme duress. Her arc embodies the overarching themes of vulnerability and the shattering of innocence under sustained threat.