I'm a fan!
I asked my Japanese teacher about a manga that's based on reality (not fantasy like crazy fighting or fairies or whatever), and she recommended 島耕作 (Shima Kosaku). I love it! I'm reading 課長島耕作14 (Kacho Shima Kosaku) which is from the early 90's, and since then, the series became a TV show, and now, Shima Kosaku has been promoted to 社長島耕作 (Shacho Shima Kosaku). Which means that he was previously a Section Chief (課長/kacho) and is now the Company President (社長/shacho).
The manga is now in its 25th year, and I can see why! It's a great way to learn Japanese while being entertained at the same time. Even though it's taking me a lot longer to read it than a Japanese person, of course :D