High School DxD: Free Upgrade System [English]

A young man dies and is reincarnated in the ridiculous world of High School DxD with an OP system. Throughout his journey, he only seeks to live a peaceful life, but for some reason, he decides that the best way to achieve what he wants is to reincarnate as a devil under the command of Sona Sitri, since he despises Rias Gremory.