Because he has a useless skill and a noisy stomach, Fate Graphite who works as a gate keeper often gets humiliated. While helping the Holy Knight Roxy Hart, he kills a bandit and discovers that his skill Gluttony gives him the secret ability to grow stronger by absorbing the skills of anyone, human or monster, that he kills. Working for Roxy now, Fate begins his journey to grow stronger, but learns that if he delays killing for too long his skill will cause him to go berserk. Along the way, he discovers a sinister plot involving his own skill, his friends, and his own family's lineage.
