Hikaru first appears to stop the person impersonating Daichi Sumeragi. The fake Daichi had stolen Hikaru's beyblade from his younger brother, who had "borrowed" Spike Lizard prior to it being stolen. He challenges Daichi and defeats him. His little brother invites him back to their home, revealing that they are a very wealthy family, where Hikaru battles him. It is also revealed that he has a group of fan girls that follow him around. Daichi is able to defeat Hikaru, but the wings of his Gaia Dragoon break off.
It is also revealed the Hikaru knows Kenny through the internet when he get him to help Daichi repair his beyblade. Daichi is able to repair his beyblade, but the 'wings' are not activating. To help him, Hikaru challenges him to another match and is able to use his Burst Cutter.
Hikaru later reappears during the G.B.C. Japan Preliminaries in Volume 10 when he is defeated by Kai. He also explains to Daichi that the purpose of the tournament was to form a tag team.
He makes his last appearance to cheer on Daichi in the final battle of the G.B.C.
Hikaru's bit beast is Spike Lizard and has the ability to camouflage into any natural environment. His beyblade is also equipped with small wheels that allow his beyblade to roll to the side and dodge his opponents attack. He is always seen wearing his roller blades.
Mamoru Tomonji is Hikaru's younger brother.