Summer Wars (Japanese: サマーウォーズ Hepburn: Samā Wōzu) is a 2009 Japanese animated science fiction film directed by Mamoru Hosoda, animated by Madhouse and distributed by Warner Bros. Pictures. The film's voice cast includes Ryunosuke Kamiki, Nanami Sakuraba, Mitsuki Tanimura, Sumiko Fuji and Ayumu Saitō. The film tells the story of Kenji Koiso, a timid eleventh-grade math genius who is taken to Ueda by twelfth-grade student Natsuki Shinohara to celebrate her great-grandmother's 90th birthday. However, he is falsely implicated in the hacking of a virtual world by a sadistic artificial intelligence named Love Machine. Kenji must repair the damage done to it and find a way to stop the rogue computer program from causing any further damage.
After producing The Girl Who Leapt Through Time, Madhouse was asked to produce something new. Hosoda and writer Satoko Okudera conceived a story about a social network and a stranger's connection with a family. The real-life city of Ueda was chosen as the setting for Summer Wars, as part of the territory was once governed by the Sanada clan and was close to Hosoda's birthplace in Toyama. Hosoda used the clan as the basis for the Jinnouchi family after visiting his then-fiancé's home in Ueda.