You have fused your being with a demon, combining a demon's power and Immortality with a human's self awareness and Knowledge of good and evil, allowing your body and soul to become more powerful, growing with experience to make you a being that can kill Gods. This has no upper limit, with some Nahobino growing in power until they could dethrone their universe's most powerful god.
You can grant yourself new abilities known as "Miracles" with Glory, a resource earned through your deeds. This is on top of and separate from the skills you will learn & power you will gain from experience, as other demons do.
You need no equipment to perform the feats of the COMP or Demonica, being able to negotiate with, bind, and fuse demons yourself. In fact, being partly demon, you can fuse yourself with certain demons to gain their Essence.
You start at level 1, slightly above peak human and barely able to kill Imps.