Orphan Suigin encounters Riku Rei, a troubled girl from the elite and renowned Shinryou Private Academy.

Suigin works a variety of part-time jobs, but makes time to play the online game with Riku Rei. As they play, their bond grows.

Suigin learns that his only way of interacting with Riku Rei is about to end. Before the servers for Dungeon Century shut down, Suigin promises Riku Rei to help her find the flower she needs in the game.

Suigin's job causes him to miss his last opportunity to see Riku Rei in the game; Riku Rei goes to find the flower by herself.

Riku Rei gives Suigin a device that allows him to play the new game Grave Buster, and it comes with an imperative from Riku Rei's deceased father.

Thugs kidnap Riku Rei, and Suigin chases them on a bike before she is taken by a mysterious disappearing man.