Bad Boya evolves from Unbelievabou when fused with a Bad Ball.
Bad Boya now has pale blue skin and a dark seafoam green as hair with double ends. He wears shades with grey frames and pointed ends, a slate grey cape with a formed large collar, gray pants with a black belt and a golden buckle that says "BAD", and black ankle boots with four spikes on each.
In Yo-kai Watch 3: Tempura, Bad Boya is Angie's childhood friend. Even as Angie grew up and couldn't see Yo-kai anymore, he still watches over her.