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 home in Nagano. There's a catch: he needs to pose as her fiancé during the 90th birthday celebration for Sakae, the family's great-grandmother and matriarch. As Kenji juggles family introductions and a dance at the party, a cryptic math problem arrives on his phone. He can't resist solving it, but cracking the equation lets a hacker break into Oz, the virtual world that nearly every part of daily life depends on. A digital crisis spirals outward, and Kenji must team up with Natsuki's sprawling family to stop the hacker before it is too late. What starts as romantic comedy embarrassment becomes a race against time, blending humor, family drama and science fiction stakes.