The narrative opens with a scene defined by regret, chaos, and desperation. Sora resides with his younger sister, Ann, and his rather comical father. Ann serves as the soloist for her school's chorus, while Sora is an exceptional cook. He prepares his "honki" (serious) bento for his sister's school concert. As Ann begins her solo, a mysterious force creates a rift in reality, causing Ann's existence to shatter right before everyone's eyes. Sora runs in to save her, but he too becomes part of this dark ritual. Sora ends up transported to a fantasy world full of gigantic mushrooms, where nothing seems certain regarding what will happen to these two.