Her husband works at an advertising agency, coming home late five days a week, constantly overwhelmed by work. Despite this, he is kind and good-natured, and Nami Sekine has been content with their life together. But one day, as cold rain falls, something inside her suddenly shifts. Overcome by an intense urge to have sex immediately, she seeks out a stranger and quickly indulges in the pleasure she craves, choosing to part ways with him once it's over. Though she knows she still loves her husband, Nami's heart has begun to fall under the grip of an uncontrollable impulse, like an illness she can't suppress. Each time she meets someone new, desire drives her forward, pushing her into a state where she can no longer control her own actions.