Gantz
One-Punch Man
Hajime no Ippo
Battle Royale
Parasyte
To lazy to put descriptions lol. But I highly recommend these. Be sure to look them up.

The end of the prologue was just released in English for 'IB - Instant Bullet'

I read it and am hooked. I loved the prologue and hope it continues to see where it goes.

I would say it is a Seinen. So much existential ponderings going on in the story.

I guess, I can just relate to how the characters think, so the actions the people take, and the reasoning behind their actions all make sense to me, despite knowing objectively that much of what they do seems contradictory or hypocritical.

Since it is only a prologue so far, it is just setting up the story, thus I'm not sure how much of trying to describe it would be considered spoilers or not.

The Gamer
A Manwha (Korean made Manga) about a guy who gains the power of an RPG player in real life. To be able to level up and train, learn skills from books and even have your own handy inventory with unlimited space. The dream of most RPG players in one series.

It's a really fun series to read, watching how this guy becomes super OP in real life and them using a bunch of gaming references.
http://www.mangahere.com/manga/the_gamer/