Kenji, the teenage hero of "Summer Wars", is an alternate for the Japanese Math Olympics team, but math is the only thing he's good at. He works part-time doing maintenance for the global computer network Oz, so he jumps at the opportunity when his pretty classmate Natsuki offers him a job--until he discovers she wants him to pose as her fiancé at her grandmother's 90th birthday celebration. Kenji has his hands full coping with Natsuki's large, eccentric family, who constantly refer to their samurai ancestors as they squabble with each other. But when a malicious AI program known as The Love Machine attacks Oz, Kenji has to solve a series of complex mathematical puzzles to prevent the cyberterrorist from causing a disaster. Mamoru Hosoda captures the oppressive heat of the Japanese summer in the sequences involving Kenji and Natsuki; Oz is rendered in a brightly colored, hallucinatory style. Hosoda worked with Takashi Murakami on the "Superflat" project, and the avatars that populate Oz reflect its depraved cuteness. "Summer Wars" was a critical and box-office hit in Japan, and deserves a wide audience in America. Hosoda, who also made "The Girl Who Leapt Through Time" (2006), is clearly one of the most interesting directors working in Japan. (Suitable for ages 12 and older: brief nudity, cartoon violence) "--Charles Solomon"