The narrative centers on Yuzuki, Matsuri, Nono, and Makoto; a quartet of childhood chums who converge at their old stomping ground, Mochitsuki Academy, which currently lies abandoned. The storyline is rooted in an offering by Haikuo-Soft. As juveniles, the foursome interred a time capsule beneath a specific tree, vowing to return after three years. Finally, the appointed date has arrived.