Kurenai no Ookami to Ashikase no Hitsuji

Crimson Wolf and Fetters of Sheep (紅の狼と足枷の羊, Kurenai no Ōkami to Ashikase no Hitsuji) is a Japanese manga series written and illustrated by Seishi Kishimoto, creator of 666 Satan, and was published in Shōnen Rival.

Plot
All humans are wolves in sheep's clothing and the same applies to Douchinji Youichi, a boy who always daydreams about various things, but never says anything out loud. One day, upon seeing a red full moon, a girl came dashing at him before punching him with a silver knuckle, knocking him unconscious and unable to really remember the incident. The next day, a new student, Akatsuki Ayame, joins his class.

On his way home, Youichi discovers that the girl who punched him is Ayame, and her silver knuckle draws out what she calls a "wolf", a person's inner thoughts or desires, from a "sheep", the superficial mask which restrains the inner "wolf" from surfacing. However, when someone is full of desires and becomes obsessed with their inner thoughts, the "wolf" outgrows the "sheep" and the person will be able to see the World of Red Moon. The girl explains that she doesn't have a "sheep" and would like to have one, so she requests Youichi to become her "sheep". Youichi agrees to it, marking the beginning of a story of the red riding hood who devours the wolf.