Starting with I AM A HERO by Kengo Hanazawa.
I don't recommend the story for young teens as it does contain graphic scenes of violence and other adult situations including language and nudity.

20180902_175318 by Michael Foertsch, on Flickr
I was first attracted to this title only because I was watching the Walking Dead on TV. I like the idea of a post apocalyptic world full of zombies being presented in film and literature. I hope I never live to see the real thing though! Now I'll admit that for whatever reasons, I have not read any of the Walking Dead comics - I've only watched the TV series. There are things I like and dislike about the TV series, but that's for another time and place.... I really just wanted to mention that the Walking Dead is what got me interested in I AM A HERO.

20180902_171526 by Michael Foertsch, on Flickr
The artwork is what you'd expect from this sort of Manga, full of intricate details. I do wish it were a larger page format so I could enjoy the artwork that much more.
Dark Horse has published the stories in omnibus format - each book contains 2 volumes that originally were released in Japan (each volume contains numerous chapters). According to Wikipedia, the manga was serialized in the Japanese manga magazine Big Comic Spirits published by Shogakukan starting in 2009. There are currently 7 Omnibus volumes out by Dark Horse, and there should be another 4 volumes by the time the story ends.
The books read in typical Japanese manga fashion, from right to left (the 'back' is the front, and the 'front' is the back).
The story is a typical zombie story, but as I found out not too long ago, it will eventually have a bit of a twist in the coming issues... so it's not your typical zombie story. We're already starting to learn more of that in the most recent issues.
The plot according to Wikipedia:
One of the things I do like about the story are all the quirky things that shout out Japan. It certainly helps if you've been to Japan, or know something about Japanese culture, in order to catch all the little things that add to the atmosphere of the story. One recent example that stands out is a letter of apology that one character writes after they have stayed at an abandoned campground. The letter ends with, "We apologize also for apologizing in such a hastily written letter." Typical Japanese etiquette at it's finest.The story begins with Hideo Suzuki, a 35-year-old manga artist assistant, whose life seems to be stuck around his exhausting but low-paying job, unfulfilled dreams, strange hallucinations and unsatisfying relationships. He sees himself as a supporting character in his own life, and has low self-esteem, resulting in frustration.
One day, the world as Hideo knows it is shattered by the presence of a disease (nicknamed ZQN) that turns people into homicidal maniacs who resemble and behave like zombies, and whose first instinct is to attack and devour the nearest human. Armed with only his sporting shotgun, he runs for his life, meeting strangers along the way. For a while, he and his companions struggle to stay alive, while questioning their moral choices. In the end, only three of them remain and drive all the way to the top of Mt. Fuji to be saved.
Below are all the Omnibus covers so far, and the back cover synopsis.
(I will add the final volumes as they are released. The next volume, #8, is due out in November 2018)