At the end of 2025, having grown accustomed to life in Tokyo and almost losing touch with the changing seasons, "I" receive a message from Mitsuri, my high school sweetheart, after five years. There was no clear reason for our breakup; the long distance had simply caused us to drift apart. However, a lingering feeling of "first love" remains in my heart, making me feel guilty towards my current girlfriend. The place chosen for our reunion is Yokohama.