Near the end you can see Beem paint with their tail instead of a brush; I think it's safe to assume their bloodline magic is involved.
They are from a family of artists, after all; I wouldn't be surprised if they all imbue magic into their works
Data analysis: Aoki's lackeys; two students that hang around the gym a lot.
Guys hanging with Takamura: Itagaki's dad and a hobo that frequents the usual boxing hall. Takamura hangs out with both occasionally, but never together before.