Mamono Kurai Ranking Saikai no Boukensha wa Mamono no Chikara de Saikyou e

This is the story of how the weakest adventurer becomes the strongest— Essen, the perpetually lowest-ranked adventurer, heads to dungeons almost daily to improve his ranking. However, his [Gift] was a dud that merely allowed him to eat monster meat without getting sick. Unable to hunt monsters, his ranking remained at rock bottom. One day, while trying to save a girl being attacked by a monster, Essen bites the creature and awakens to the true power of his [Gift]— The hidden ability of his [Gift] was to use the powers of the monsters he had eaten! The tale of the weakest adventurer rising to power using monster abilities begins here!!