Quote from Sapphiresky
Haha, there's a lot of characters similar to this, but it's rare to find ones that are completely overpowering and undefeated for the whole series.
(I was gonna list hunterxhunter but I see you've already read that. God I love that series! Hisoka really is the best, especially for this kind of cha ...
I think Mephisto is perfect, they might be scared of him, but it's pretty clear he overpowers Rin (and pretty much everybody except Satan) by much,
Spoiler (mouse over to view)
seeing how his little brother kicked Rin's ass once he went full power and It has been made clear that Mephisto is stronger than every other royal demon but Satan
, but I'm reading it already.
Level E is not what I'm looking for exactly, but it has been on to read list for a while and I never got to read it, so I'm giving it a try, thank you!.