Hijiri, who lives in Tokyo, has a habit of staying at her younger sister's house in the countryside every summer. Each time, her brother-in-law, Seiji, harbors strong feelings for her, though he's never fully acknowledged them. One day, Seiji suggests going to gather wild mountain vegetables, claiming he's bored. Hijiri, seemingly interested, agrees to go with him. After several hours of happily harvesting in the deep mountains, they're caught in a sudden downpour and take shelter in a nearby mountain hut. With no one coming to pick them up, they're forced to spend the night alone together. In that intimate situation, Seiji can no longer suppress his hidden desires and confesses his feelings to Hijiri.