Two kids fall in love, then their parents fall in love, and suddenly they're about to become siblings. The only escape is a parallel universe, but every jump between worlds costs something they can't get back. This movie doesn't ask if they'll find a universe where they can be together, it asks what they're willing to lose to find out, and by the ending you'll understand why that question matters more than the answer.

Koyomi Hidaka goes to live with his father after his parents divorce, and through his father's work on parallel worlds he meets Shiori Sato, the daughter of another divorced researcher. The two grow close over the years and hope to marry someday. Then their parents decide to marry each other, which would make Koyomi and Shiori stepsiblings. Refusing to accept this, they use their parents' research to flee to a parallel world where they are not related. Crossing between dimensions is common in their world, but it has consequences, and theirs threaten the very future they wanted. The sci-fi romance movie is adapted from a novel by Otono Yomoji and was released alongside a companion film.