|First appearance||A Perfect Match|
|Voiced by|| Kiyotaka Furushima |
|Age|| 12 (Battle Brawlers) |
15 (New Vestroia)
|School level||1 [ (Senior high school / high school (高校 Koukou))]|
|(Main attribute used by this battler)||Subterra|
He becomes the top tenth brawler in the world before he becomes one of Masquerade's henchmen, when he's exposed to the Silent Core. He reappears as Masquerade's henchman, along with Komba, and battles Julie and Shun. He loses; however, he still remains an antagonist. As Masquerade's henchman, the others often make fun of him since he is the only one in double-digits and is lower-ranked than the rest of them.
Later, when Julie attempts to bring him back to his senses with a battle, he nearly sends Julie and Gorem to the Doom Dimension, but after seeing the toy he had given her when they were young, he still defeats her but right before Gorem is sent to the Doom Dimension he takes out the Doom Card. He is then freed from Naga's control and Billy explains to the Brawlers how he first met Naga.
He agrees to help everyone stop the minions of Naga, slowing down Rabeeder but not stopping her from getting closer to the city. He returns to help Julie and Nene fight the Subterra-Haos Tricloid, resulting in him and Julie forming a girlfriend/boyfriend relationship.
Billy is first mentioned when Julie says that he was traveling the world to learn from famous athletes, and he was currently living in Spain.
In episode 10, he moves to Africa to build schools.
He appears again in episode 37, where he and Julie brawl against Ace, but they are easily defeated.
Billy brawls using Subterra Bakugan. He and Julie have most of the same Bakugan.
- Subterra Cycloid (Guardian Bakugan)
- Subterra Wormquake
- Subterra Hynoid
- Subterra Tuskor
- Subterra Rattleoid
- Subterra Centipoid
- Subterra Manion
- Subterra Mantris
- Subterra Terrorclaw
- Subterra Saurus
- Billy calls Julie BakuBabe which seems to annoy Julie.
Although Billy has been shown to be a strong brawler and ranked highly, most of his battles have been losses. His battles have also involved Julie Makimoto in some way, with six out of seven battles being against, or alongside her.
|Bakugan: Battle Brawlers|
|Shun Kazami and Julie Makimoto (Tag with Komba O'Charlie)||Lose|
|Tricloid (Tag with Julie Makimoto and Nene)||Win|
|Ace Grit (Tag with Julie Makimoto)||Lose|