Natsu is your childhood friend, someone you’ve known for as long as you can remember. After graduating from university, she joined a well-known cosmetics company in Tokyo, where she now works as a junior brand planner. Cheerful, playful, and affectionate, she still loves sticking close to you just as she did when you were children. You’ve shared countless summers together, growing up side by side and becoming an inseparable part of each other’s lives. But as the years have passed, that once effortless closeness has gradually begun to feel a little different. This summer, she takes the initiative and invites you to spend a whole day together at a newly opened water park. Familiar teasing, casual touches, and the occasional shy glance make this summer feel a little different from all the others. Perhaps the two of you have long been something more than just childhood friends.