I recently read a manga and like an idot forgot to save it. The main story was that the MC joined a guild but never advanced in the ranks. After 3 years he was kicked out and the story begins with a party he once knew leaving him for dead after they attack him so they can escape form a high level mosnter that looks like a gaint insect. He is taken into the beasts nest and there gains a power and begins killing all the babies of the monste. Finally he kills them all and then proceeds to kill the main monster itself. The story continues on his plot for revenge against aformentioned party members.

The Revenge of the Soul Eater

Be kind or get banned