Violence Jack is the main protagonist and titular character in Go Nagi's Violence Jack manga and OVA series.
Background
Violence Jack is a giant, 10 to 12 ft seemingly unstoppable inhuman man, who after been uncovered from under some rubble, wanders the wastelands of a destroyed post-apocolyptic Kanto, which had been destroyed by the "Great Kanto Hellquake". Kanto is now ruled by a psychopathic, samurai warlord named the Slum King, who quickly becomes a rival to Jack and the two clash multiple times, with Jack ultimately emerging victorious in the two's final fight. Jack fights several other enemies throughout the manga and OVAs. It was later revealed that he was the reincarnation of Akira Fudo/Devilman.
Jack possesses many abilities such as massive strength, skill with his giant Jack knife (of which he gets his name), agility and an incredible ability to heal most wounds almost instantly.
Formes
Violence Jack vs Enma-Kun. Its like Mortal Kombat Vs DC Universe. Only it has the gore and b0ning we wanted!
Jack has several avatars roaming around the Mad Max wasteland. They usually take the forme of a Golden Bird to travel easier. They also have taken on other forms such as a puppy or a rabbit or snake.
Girl Jack
This forme is a beefed out babe wearing little and usually getting B0NED by someone or [[Kapaeru}something]]. She fights with a whip but also has blades.
Kid Jack
ateen/tween who makes Gohan look like a CANDY A55 in buffness(and coolness. and manliness. and straightness. ect) He fights with blades but I think he used a bow and arrow once(or was that girl jack?) He also mo lested by Yukiko (but she's like a hot older woman) and he helps some malcontent teens (and a sexy half naked chick(no not arianna grande)) lean that its cool to stay in school)
Barbarian Jack
Its like a fusion of the 1st 3 versions of him/her
A 20 something looing jack who only appears in in one chapter.
Full Forme
Like in Kirby 64 where the hero, the chick and the macguffin combine, in the final battle of Violence Jack, the 3 jacks fuse into their true forme! Sometimes he's a big buff guy! Sometimes he's a Bird. And sometimes he's a sexy buff babe! but his true forme is... Demon warrior! the Devil man!!