Ayashimon (アヤシモン) is a Japanese manga series written and illustrated by Yuji Kaku.

Maruo Kaido (海堂 マルオ, Kaidō Maruo) is an unusually strong boy and an avid manga fan who dreams to be a "manga hero".

One day, he meets Urara (ウララ), an oni ayashimon—a kind of yōkai able to shapeshift into humans—chased by an ayashimon yakuza gang.

After Maruo easily defeats the gang, Urara, impressed by his strength and by the fact that he is a simple human and not an ayashimon, recruits him as the first member of her yakuza group.

Maruo, hesitant at first, accepts her offer, realizing that he can experience life as a manga protagonist following the path of a yakuza.