Summer Wars is a 2009 Japanese animated film directed by Mamoru Hosoda and produced by Madhouse. The movie follows Kenji Koiso, a high school student who works part-time as a moderator in the virtual world of OZ. Kenji gets invited by Natsuki Shinohara, a popular girl from his school, to her family's estate to celebrate her great-grandmother's 90th birthday. Initially hesitant, Kenji agrees and is surprised to find out that Natsuki wants him to pose as her fiancé to impress her family.
During his stay, Kenji receives a coded message through OZ, which he deciphers overnight. The next day, Kenji is shocked to find out that OZ has been hacked by an unknown entity. The hacker then proceeds to take control of the infrastructure and systems of the world with OZ as its headquarters. In a race against time, Kenji and Natsuki unite their family and friends to battle the hacker and save the world from disaster.
Summer Wars is a visually stunning movie that tackles themes of family, love, and the power of technology in our lives. The film also highlights the dangers of relying too much on technology and not valuing real-life interactions. The characters are well-developed, and the storyline is engaging and emotional. Overall, Summer Wars is a must-watch for anyone who loves science fiction, animation, or Japanese culture.