Fire Punch – MangaPark [Fujimoto Tatsuki]

Found this absolute masterpiece of violence! It reminds one of the Fist of the North Start combined with the insanity from the Freesia by Matsumoto Jiro. Throw in the immortality from the Ajin as well. (This is very oddly tagged as Shounen being from Jump Comics, but the cruelty and theme is definitely Seinen level.)