If you liked the Zetman manga, the Anime-Planet community thinks you'd like:
If you like either Zetman or Akumetsu, give the other one a try. Both revolve around an invincible male protagonist that virtually cannot die. Both mangas offer realistic themes and are very explicit in blood and gore. While Zetman focuses some on relationships, Akumetsu deals with government corruption.
There is something about both of these that just draws you in. Give them a try.
Besides both of the main characters seemingly immortal life, the mood of Zetman and Akumetsu is incredibly dark. A dark aura shrouds each character that feels mass evil yet both protagonists are heroes. Mainly the feeling is the same. Tons of brutal gore and mass death, both have a fast pace plot with two unique characters. These two mangas are rich in art, action, and plot development. If one was read then by all means take a trip into the other.
Born beneath the gallows tree from which his dead mother hung, Guts has always existed on the boundary between life and death. After enduring a terrible childhood, he spends his adulthood in brutal combat, pitting his strength against others in order to build his own. Life is simple enough for Guts until he meets Griffith, the inspirational, ambitious, and beautiful leader of the mercenaries, the Band of the Hawk. When Guts loses to Griffith in a duel, he is forced to join the Band of the Hawk, and, despite himself, finds a sense of camaraderie and belonging amongst them. However, as Griffith leads his soldiers from victory to victory, the bloody wars and underhanded politics reveal a side to him that nobody quite expected. Very soon, what seems like a straightforward march for conquest becomes a harrowing struggle for humanity and life itself. Can Guts, a simple warrior, defend those who have come to mean the most to him, all the while struggling not to lose to the darkness he has carried with him his entire life?
Berserk and Zetman are both fantastic manga and closely resemble each other. One the things that are most similar is the design. The dark shading on characters and backgrounds are what caught my eye.
Another element the same is the atmosphere. Berserk leaves hardly any room for jokes and play, which is also the case with Zetman. Zetman is a serious manga with lots of gore and death and maintains that "down to business" mood. If Berserk or Zetman chapters are taking to long, give the other a chance, there just awesome. (Berserk still #1)
Akira Inugami is a teenager with a secret: while his slender build makes him appear weak, he is in fact a werewolf with incredible senses, an inate fighting ability, lightning-fast reflexes, and an inability to sustain damage. After a series of dangerous incidents leads to him being expelled from previous schools, Akira transfers to Hakutoku Academy with a desire to be left alone. However, on his first day he instantly becomes the target of the school's most infamous delinquent gang, led by the fearsome Haguro. On top of that, his homeroom teacher, Aoshika, has taken a keen interest in the mysterious teen and refuses to leave him in peace. Now with enemies to fight at every turn and Akira finding himself unable to let the beautiful Aoshika suffer on his behalf, this lone wolf's hopes of a quiet, solitary life seem like little more than a pipe dream.
If you like either Zetman or Wolf Guy, give the other one a try. Both revolve around an invincible male protagonist that virtually cannot die. Both mangas offer realistic themes and are very explicit in blood, gore, and in the case of Wolf Guy, nudity and sexual references. Both mangas deal with some relationship aspects of the male lead.
Try them out, you won't be disappointed.