Digimon Adventure: Our War Game!

When a deadly virus Digimon causes mass havoc on the Internet, it's left up to just a few of the DigiDestined to stop him, and save Tokyo from an incoming missile attack.

Synopsis
While the DigiDestined are on summer vacation in the real world, Izzy Izumi discovers a virus on the internet infecting a Digi-Egg. At the same time, Tai is trying to apologize to Sora Takenouchi for getting her a hairclip for her birthday in an e-mail. Izzy arrives at Tai's house out of breath, telling Tai about the newly-hatched Digimon. Tai and Izzy use Tai's dad's computer and monitor the Digimon until Gennai appears in a transmission from the Digital World. He sends Agumon and Tentomon to help stop the corrupted Digimon. They put up a good fight until Keramon Digivolves to Infermon and defeats them.

Tai tries furiously to contact and alert the rest using a phone, but when Keramon begins to dial as many numbers as can be pulled up over the PSTN, Tai's Internet connection is disconnected. Faced with this dilemma, Tai sees a television report on suggestions for the use of the voice mail system as an alternative means of communication over phone lines; using this method, he ends up getting only Matt Ishida and his brother T.K. Takaishi, who are on vacation at their grandmother's house in Shimane. They find a computer in a local shop, and ask one of the employees for permission to use it; taking pity, he takes the two and his computer to a barber shop with an Internet connection and upload Gabumon and Patamon onto the net. Infermon Digivolves to Diaboromon after Agumon and Gabumon Warp Digivolve to WarGreymon and MetalGarurumon but then they slow down because of the massive amount of e-mails being sent to Tai and Izzy. Tai slaps the computer and freezes it leaving WarGreymon frozen and defeated.

Diaboromon then starts multiplying and sets up a timer for 10 minutes as he forces the Pentagon to launch two nuclear missiles: one headed for Colorado, the other for Tai's neighborhood. WarGreymon and MetalGarurumon wake up and race to defeat Diaboromon, only to find over a million copies of him. Every single copy fires and blast them until they lie defeated. Tai and Matt mysteriously enter their computers and talk to their Digimon. WarGreymon and MetalGarurumon DNA Digivolve to Omnimon who easily defeats all but one Diaboromon. At one minute to go, Diaboromon is still too fast for them to hit, but then Izzy forwards him the e-mails, slowing him like it did to the other Digimon. At the very last second, Diaboromon is destroyed, disabling the missiles.

Other notes

 * According to the film, while Tai and Izzy are at home for summer vacation:
 * Kari Kamiya is at a friend's birthday party
 * Joe Kido is late for a middle school entrance exam
 * Sora Takenouchi is avoiding Tai, but is at home
 * Mimi Tachikawa is in Hawaii with her family
 * Matt and T.K. are at their grandmother's in Shimane
 * The real-world town of Shimane was merged into the Shimane Prefecture capital of Matsue in 2005.
 * The term "NTT system" may be a reference to NTT DoCoMo, the largest telecommunications network in Japan.