Mio, who divorced 10 years ago, raised Yuuki by herself. She worked tirelessly so as not to make him feel sorry, and before she knew it, Yuuki was in his final year of university. While raising a child was a relief, Mio lost her goal. However, Yuuki invited her to a hot spring trip to express his gratitude for everything so far. Mio and Yuuki set off on a graduation trip for just the two of them.