Katekyō Hitman Reborn!

Prefer signatures with out borders
What I like is that effect on his body. I think it looks really neat but the face needs to get cleaned up a bit imo.
Background is sort of plain. Try make it more detailed and maybe try adding some flow to it.
I'd try smudge in the render a bit maybe to get some better blending
IMO those bubbles can just go. They look 'awkward' there and don't suit the style at all imo
But then it's be very plain so you'd need another way to fill in the space. Maybe some clipping masks and some light spots will do the trick
Lighting is rather good but I'd maybe burn the sides a tad bit more and dodge that light area near the render