Hikaru Himuro

Anime/Manga Season 1:
The number one Dragon Drive player in the world, and Reiji's biggest rival. He was recruited by RI-ON as a soldier, but doesn't seem to care for anybody or anything. His true intentions are unknown, and Reiji is the only person he sees any interest in. He later defects from RI-ON to pursue Reiji with the intention of challenging him to a showdown. He is the reigning superchampion.

Manga Season 2:
Having stayed behind in Rikyu since the last world crisis, he has been training himself for his showdown with Reiji. At Meguru's request, he returned to Earth to do two things:(1) open the portal that would lead the Raikou-ou masters into Rikyu, and (2)return Chibi to Reiji.

Manga only:
Later on he is recruited by RI-ON as a soldier, but he does not care for anybody or anything, especially the battle between RI-ON and the Dragon Drive world. His true intentions were unknown.
Soon after he defects from RI-ON to follow Reiji during the search for Shinsaber with the intention of dueling Reiji one on one to see who is superior. He would follow Reiji even if it means going through a haunted house or passing a trial to determine who owns the right to Shinsaber.