Vio wants to call it a day at her café. But just before she leaves, she notices a (fake) Rubik's Cube that a guest must have left on a table. When she reaches for it, she unintentionally opens a portal that pulls the cube into itself, with her along with it. When she and the cube land in a forest, the portal closes and disappears as suddenly as it appeared. Surprised and visibly confused by this event, Vio wants to get back as quickly as possible, but that doesn't turn out to be so easy. In her attempt to return home through a portal, she instead travels through various worlds and places. There she will meet many bizarre characters, such as the depressive Death, who, as an undead deuteragonist, will accompany Vio on her journey again and again. He has his own story, which will influence Vio, and which in turn will influence the entire story.