Ashitagirl becomes Damajor's source of inspiration thanks to her ability, which in turn causes him to evolve into Damajor Nine. However, when Ashitagirl turns to cheer Marunugget when losing a baseball match in the Yo-kai World, Damajor reverts to his original form out of shock.
Damjor made his debut in EP167. Before he was a Yo-kai, he was one a human boy who was afraid of catching the ball. While he carried baseball bats, he was flipped backwards to his death. Nate summoned Ashitagirl to cheer him up, which caused him to evolve into Damajor Nine. Later, in a baseball match in the Yo-kai World, after Damajor strikes Marunugget once, Ashitagirl turns to cheer the later instead. Out of shock, Damajor Nine returns to being Damajor. He later sorrowly gives Nate his Yo-kai medal and leaves into the horizon.
"Damajor" is a wordplay on the English major and dame ja! (だめじゃ！, "it's no use!", "this is hopeless!")