Coworkers Ayaka Muto and Yuuki are secretly involved in a passionate affair, stealing moments together whenever work allows. Both are married with families, leaving them little freedom to meet openly. Yet they share a mutual dream: to escape reality, even just once, by taking a hot spring trip together—just the two of them. For months, they've meticulously planned this getaway under the guise of a business trip. Finally, the day arrives. Meeting at the station, they shed their work suits, change into casual clothes, and eagerly board the bullet train. Upon reaching their destination, they immediately fall into each other's arms, locking lips as they plunge into their own private world.