The artwork is great. The MC is great. The female(?) sidekick is awesome. Would I recommend it for most people? Eh.. a few things are hindering this from greatness.
One is the Bleach effect. The action in this story is set up pretty similar to Bleach. Lots of colorful characters fighting with bizarre moves. The visuals are great but the hits don't carry weight since you can never gauge how much things do damage. These characters can recover from anything if they are strong enough at the time or something. Only the author knows. Nothing consistent to visually see it so you lose that critical hype factor in the action. Oh he's on his last breath? Nope, he upgrades midfight and completely recovers with a comeback.
Parallel storylines. They are great when done right. Here? A bit too dissociated. These storylines do contribute to each other but so little and the build up is so slow that many times you wish the author just skips a section entirely or condense it since one story is usually way better than the other.
Too many characters. Although this story tries hard to get you hyped up for cigarette man vs tongue man, these characters just had too few panels to get me invested into the fight. The same goes for so many others that you wish the author narrowed his focus more.
The end, although having a nice twist, was rushed too hard. New characters start falling from the sky. Backstories for new and minor characters get thrown at you. Our MC starts taking a back seat and the author still expects you to still care for what's happening.
Also this is supposedly the first season of 3 total. The second is Hellper 2 - Killberos which is a prequel. This is a big NO NO the author pulled. Hellper ends so sloppily and now you expect us to read a 103+ chapter prequel? I'm stopping the series here and I'm can't recommend picking up this series.