Yuuya Tenjou, a boy tormented by bullies, resides with his beloved grandfather. After enduring another round of bullying, he takes a break from school to recuperate. During his absence, he decides to tidy his grandfather's home and stumbles upon a room he had never explored before. Inside, among his grandfather's collection of artifacts from global travels, Yuuya discovers a peculiar door hidden among the items. Driven by curiosity, he opens the door, leading to an unexpected revelation...