Summer Wars

A shy high school senior and mathematics prodigy is invited by a female classmate to spend the summer at her family's home in Nagano. The girl's family, part of a long-standing clan, is gathering to celebrate the 90th birthday of their energetic matriarch. He soon learns his supposed "summer job" is to pose as her fiancé for the festivities. While trying to maintain the charade, he receives a complex mathematical problem on his phone and solves it out of curiosity. The solution inadvertently triggers a security breach in Oz, a program that manages most aspects of daily life. He and the girl's family must work together to prevent further damage from the hacker.