Marina and Uchimura are coworkers sharing the same office, each living their daily lives while maintaining their respective families, yet harboring hidden feelings for one another. Unable to pursue a genuine romantic relationship, they instead chose the path of a mutual affair, engaging in a physical relationship behind closed doors. Always avoiding the eyes of others, they've continued their secret trysts. Their shared desire is simple: "Just once, we want to forget everything and completely lose ourselves in sex." To fulfill this dream, they plan an illicit getaway under the guise of a business trip. On the day of departure, meeting at the station, they shed their suits, change into casual clothes, board a limited express train, and head to a secluded inn. The moment they arrive, they passionately kiss, craving each other's lips, marking the beginning of a new adventure.