Shinji, his father, and his father's new wife Reiko embark on a one-night, two-day hot spring trip. Along the way, at a rest area, Shinji becomes flustered by Reiko's sensual charm. However, after arriving at the inn, his father leaves abruptly due to work. Left alone together, Shinji freezes up with nervous tension—but Reiko takes notice and begins making advances toward him. As night deepens, Shinji's excitement builds. Lying under the covers, he eagerly anticipates the beginning of a thrilling new journey.