|First appearance||Critical K.O.|
|Voiced by||Masanori Machida (Master Shimo)
Yuuki Hayashi (Mister Down)
Master Shimo makes his debut in the first episode where he acted as a referee in the Bakugan Dojo brawl of Harubaru Hinode against Raichi Kuronashi. He declared Harubaru Hinode as the winner and gave him metal cross parts as a prize.
In the ninth episode, it was revealed that Master Shimo had a fierce rivalry against Master Jyou while they were under the tutelage of Quilt. Quilt gave Shimo the Dojo despite that Jyou is a better brawler because of the latter's inflated ego. As a result, Jyou left the dojo and vowed revenge against Shimo. The scene also reveals that Master Shimo used to be a Pyrus Brawler with a Blue Blaze Gus Burnan as his Guardian Bakugan.
- Aquos Butta Gill (Guardian Bakugan)
- Blue Blaze Gus Burnan (Former Guardian Bakugan)
- Pyrus Flare Dragaon (Given to Harubaru)
- Darkus Destroy Munikis (Given to Raichi)
BakuTech! Bakugan (Anime)
Master Shimo's name is taken from the Japanese Word Shimo (下, Shimo?) which means Under or Lower. It directly contrasts the meaning of Master Jyou's name. The alias of "Mister Down" was derived from this.
- A namesake of his appears in BAC tournaments around Japan as the tournament referee.