Kenji goes with his classmate Natsuki to her Grandmother's 90th birthday celebration in Ueda. Whilst there he's introduced as her fiancé to all her family.
Kenji receives an email with a mathematical code and cracks it, resulting in an artificial intelligence "Love Machine" to run havoc on the virtual reality world OZ which coincides with the real world.
The longer Love Machine is left to its own devices, the smarter and more powerful it becomes. By taking over avatars in OZ it has access to high class positions in the real world and is able to interrupt emergency services and military intelligence alike.
During this it disrupts any notification regarding Natsuki's grandmother's condition, resulting in her death.
Kenji and the family work together to come up with a plan to beat Love Machine once and for all. They confront it and manage to capture it but due to one of Natsuki's relatives interrupting with the supercomputer preventing them from stopping Love Machine.
Love Machine redirects a satellite to crash into a nuclear power plant.
They confront Love Machine one last time in a game of Koi-Koi in OZ's casino world, wagering their accounts to win back the world's avatars from Love Machine. At one point Natsuki nearly loses all of her winnings but the remainder of OZ users offer their accounts for her to use, and ends up winning.
The coordinates for the falling satellite is redirected to the family's estate and King Kazma beats Love Machine once and for all.
Kenji activates the GPS code to redirects the satellite away from the estate, but only slightly. The impact destroys the estate's entrance and causes a geyser to erupt.
The rest of the family arrive, celebrating the victory as well as Natsuki's grandmother's birthday. Natsuki kisses Kenji after they confess to each other.