Yes, I'm looking for stories that span throughout the life of the protagonist(s). They can be about the person's entire life or just about the later/selected parts of their life.

The story must contain:

-a number of years of their lives: 5 to 10 years is a minimum... though I'm looking for something like "over 10 to 20 years"

-be considerably thoughtful and/or thought-provoking in a matured manner(Absolutely no fighting in terms of relationships unless they truly get over it or deal with it in a matured manner). And I mean thinking and acting about the matters, NOT preaching about moral values and crap, or preaching how a system is terrible because "blah blah blah... shit happened... so blah blah... the system is terrible". Haha... I had to sit through moral education classes as a child, soo... I'm incredibly intolerant towards stuff like this.

-if there is any emphasis on sex or sexuality in it, these themes must be dealt with thoughtfully as well.

The story must not:
-contain tragedy unless it deals with said subject thoughtfully or maturedly(as in not too much dwelling upon said subject, characters know how to move on, or if there are reasons why the characters cling on for revenge or vengeance, then those reasons must make a lot of sense and not be too melodramatic, etc.)

-be sports manga. I quite frankly am not interested in sports techniques and stuff.
-be one of those long-ass fighting mangas where "thought-provoking" equates "bashing people's skulls inside out" and where quoting psychology yanked from movies and books means "anything that sounds complicated and deep(but which actually is nonsensical and ridiculous)"

-be typical manhwa where deep equates mushy-mushy romances that freak me out and thought-provoking equates... REVENGE. I don't mean "revenge" but "REVENGE" where it's more like "you mother, I'm going to kill off your entire family/rape your sis/commit some hedonistic or machiavellian act while spawning philosophical stuff about this and that".

-be mainstream shoujo or shounen, unless there is something redeeming about it. Just the same, I'm not too interested about school-life unless it's dealt with maturedly too.

• contain conspiracies. Errr... I'm really not into Monster or 20th Century boys kinda conspiracies.

Something like:
Vagabond(the themes of morality, philosophy and so on... are really worth it)
Complex
New York New York
Haruka na Machi e
The Changelings (it starts off more as a comedy but over the time, it does deal with the subject matter quite thought-provokingly.)
Intersexuality
Hourou Musuko

I've heard that Ikkyu might cover this but I'm not so sure since I haven't read this yet. I know that Piano no mori is about the kid who grows up but it's got plenty of drama and I'm not very sure just how thought-provoking it really is. Same about Yatteraneeze!: just not too sure how many years it covers. Also, not too sure about Vinland Saga or Historie either.

Unfortunately, I can't find anything else... hmmm.

And definitely NOT manga like:
Naruto or any of that typical shounen fighting manga
Vampire knight
Full moon wo sagashite
Beck
Mahou Sensei Negima
Watashitachi no Shiawase na Jikan(it tries really hard to be thoughtful but... dear gods, the drama... like a freaking soap opera and the preaching)
Glass no Kamen I LOVE this series but it is no way that thoughtful.
Nana

Maybe you'll find something in those threads:
click (this one seems to fit better)
click

Hrodulf and Bjornolfr, you will not be forgotten.
[img]http://i411.photobucket.com/albums/pp199/SyberAngelGabrielle/couplesig.jpg[/img]
[color=black]And if the world were black and white,
you would be my rainbow in shades of grey.[/color]

Click 'n Play!

If I had a fantasy self, it'd be a tentacle monster.

Well, the only one I can suggest is Kenji; though, it won't turn out as good as it seems it would (in this aspect).

It ends after he's spent a year, when he was suspended from high school, looking for his grandfather. I was hoping it would go the distance, but it doesn't. So, I am letting you know before hand.

[color=green]"Officially, this machine doesn't exist, you didn't get it from me,
and I don't know you. Make sure it doesn't leave the building."[/color]

The only thing that comes to mind is "Buddha" http://www.mangaupdates.com/series.html?id=10204

** Behold, as a wild ass in the desert go I forth to my work. **

Honeymoon Salad -- it's not quite what you're looking for since it probably isn't as philosophical as you want, but it does have a very subtle and mature mood and take on relationships. There are several flashbacks to middle school, though it's probably not as expansive/detailed as what you're looking for since they're only flashbacks.

Hmm... I guess that's it. Sorry I can't think of anything else, probably because I'm not a fan of those long, rambling, philosophical monologues. I either get bored or feel like the mangaka is trying to fill space with confusing nonsense in order to sound intelligent (though I'm probably just not giving mangakas enough credit). XD

perhaps Eden---its not sports, doesn't have mushy romance, quite realstic and also sad at times. Contains numerous flashbacks. It might be a bit tragic though. Deals with drugs as well. Some politics involved. Thats the best one I could come up with.

Angel Beats--best anime of the 2010 spring season

Sanctuary maybe? I haven't read it because it sounds way too 'adult' for my liking- but I think it fits your criteria pretty well.
Maybe you should also try out some of MATSUMOTO Taiyo's works. They seem to carry the realism and bildungsromane you're looking for.

Thank you everyone for the suggestions. 🙂 I'll be sure to look into them. =)

Both of these are slice of life, both very good.
See you in Eden
Onani Master Kurosawa

All of there are by the same author - very insightful.
Slow Down
The Willow Tree
Hanshin

These are just others you might like.
Hoshi no Koe
Kayou Gogo 9-ji

From the City That Never Sleeps - Not typical shoujo at all. I'm not sure how many years it spans, though.

Avatar by tassyn.livejournal.com

Reading: Kingdom, Sangokushi, Historie

Quote from Toto

Well, the only one I can suggest is Kenji; though, it won't turn out as good as it seems it would (in this aspect).]

Of course it does make you wish for more, but on the other hand the ending is really good. If it just went on it might have not turned out well.

And not to be totally off topic, here's one that just popped in my mind: Hotel. Although it's not about a person's life really but a robots, and it doesn't cover 10-20 years, but more like 1000-2000 years (or 10000 years, I forgot). Perhaps not quite what you're looking for.

Oh, here's another: Bakuon Rettou. It's covered only a few years or something (so far), but I think it fits what you look for, pretty well, unless you happen to dislike that kind of manga.

Historie will probably end up covering a whole lot of Eumenes' life (and already has quite a lot).

Whatever...

Far-off places with sweet sounding names.

Goodnight Punpun ... I'm not so sure how many years but until now it may be like 5 or 10 years
Nijigahara Holograph ... same mangaka but mainly two plots (child and adult) ... so it's more like a time skip