Berserk of Gluttony

Fate Graphite is a gate keeper who works for a noble family, but gets humiliated because he has a useless skill. Later, he kills a bandit and discovers that his skill "Gluttony" has a secret ability that allows him to grow stronger by absorbing other skills. From there, he leaves the noble family he works for and begins his journey to grow stronger and get back at those who humiliated him. Along the way, he discovers a sinister plot involving his own skill, his friends, as well as his own family's lineage.