|Full name||Brian Chaomy|
|Manga Debut||Chapter 1|
|Anime Debut||Episode 1|
Brian Chaomy (ブライアン・チャオミー, Buraian Chaomī) was an American bear used for underground fights in Bangkok, Thailand. The bear used to be omnivorous, but for a long period of time, he ate only humans, so he became completely carnivorous.
Brian is a large American black bear.
Brian was seen entering the stage of the underground arena, to the surprise of Akari. He quickly attacked while Akari was distracted and was able to scratch his face. He remembered his reason for being there and jumped on the fence of the ring to fire up the crowd, before jumping onto the back of the bear and trying to choke it to death. However, the bear proved too powerful and threw Akari to the ground, wounding him. As the bear began to eat him, Akari again remembered his childhood friend and his reasons for participating in the underground fights. Fueled by rage, he activated his bug transformation and quickly plucked one of the bears eyes. Brian swiped at him with his paw, but Akari stopped the attack and then threw the bear over his shoulder. He then jumped up and stomped on Brian's face, crushing his skull and killing him.
- In the anime series, Brian's was the first onscreen death.
- In 2015,someone asked to Yū Sasuga during an interview about Brian's fatally destiny, saying "Maybe he can still be alived, the U-NASA has been buying the greatest animals around the world due to their own interests to investigate a method to make safe the M.O Operation,so they could have saved his life"