This movie is Sakuta watching his sister take baby steps back into the world and realizing he can't protect her through it anymore. The supernatural stuff takes a backseat because the real mystery is watching Kaede decide who she wants to be, and whether her brother can let her fail. It's quiet and small in a way the first film wasn't, which means it lands harder when it does break you, the ending song plays and you're thinking about what you'd give up for someone you love.

Sakuta is nearing the end of his second year of high school, and with Mai in her third year, the two have little time left before her graduation. Meanwhile his younger sister Kaede, once a shut-in with a deep fear of ordinary classrooms, is slowly getting used to going outside again. Just as she starts to find her feet, she reveals her boldest goal yet: she wants to attend Sakuta's high school, even though her counselor thinks an online school would suit her better. Sakuta knows how hard this will be for her and wants to help however he can, but he is unsure whether it is truly best for her, or what she really wants. Kaede asks him, Mai and Mai's half-sister Nodoka to help her prepare for the entrance exam. The film is a supernatural psychological drama.