A shy kid lies to a girl's family and accidentally becomes the only person who can stop a digital apocalypse. The tonal whiplash is real, one moment you're watching a genuine romance, the next you're in a full-scale virtual war, but somehow it works because the actual stakes are a grandmother's birthday party and whether this family stays together. Hoz Iwata animates the hell out of it, and by the time you're watching Kenji fight in a digital landscape to save real people he loves, you understand why someone would break the laws of physics for a summer.
Kenji Koiso is a brilliant math student thrust into an unexpected summer when his crush Natsuki invites him to her family's countryside home. There's a catch: he needs to pose as her fiancé during her grandmother's 90th birthday celebration. As Kenji navigates family introductions and awkward dancing, a cryptic math problem arrives on his phone. His competitive nature won't let it go unsolved, but cracking the equation unleashes something catastrophic in Oz, the virtual world that runs everything from financial systems to infrastructure across the globe. A digital crisis spirals outward while Kenji finds himself caught between a crumbling real world and the collapsing virtual one, forced to rely on both his mathematical mind and an unlikely alliance with Natsuki's massive, chaotic family. What starts as romantic comedy embarrassment becomes a race against time, blending heartfelt moments with genuine stakes. The film balances humor and heart with genuine tension, creating something that works equally well as a love story, a family drama, and high-stakes science fiction adventure.