Toaru Kaijin no Katsudou Kiroku

A new breed of humans who can easily morph their bodies is starting to take over.
In this world, being a mutant is just another job. Even so, our main guy GAG is an underachiever. He keeps trying to level up, but nothing ever works out.
Then one day, a once-in-a-lifetime chance shows up...

[Translated from dlsite]