Mako was a minor antagonist in Volume 5.
He was an enormous, largely muscular man who apparently artifically carved his teeth down to a fine point, weaponizing them. He was first alluded to in V5C1's bonus scene, where it was revealed that he killed a hustler by completely eating off his neck. In the next chapter, it was revealed that he had hired 2 goon men -- Bennie P (a teenager known by Ken since childhood) and Shakes (a mentally unstable man) -- to help him intimidate a store owner who he also ate the neck of, but the neck was also eaten off.
Diego Hernandez informed Ken that Mako's 3rd target was in a warehouse; unfortunately, by the time he and Samuel Martinez got there, the victim was found. A shootout between Ken, Martinez, Bennie, Shakes and Mako occurred; Bennie and Shakes were killed in the process, but Mako was arrested.
Just as Mako was took outside, he was executed by a masked vigilante dubbing himself the "Hand of Justice".