Let's see...

Parasyte. A truly wonderful horror manga with a bit of psychology thrown in. And it raises the question of wether humans are really natural or not, which is always a plus.

Break Blade. Mecha. Where it truly shines is in the characters and their separate struggles, especially the relationship between Rygart and Sigyn.

Urusei Yatsura. A hilarious romantic comedy, and without a doubt one of Rumiko Takahashi's best. Granted, it may not be for everyone, but still...

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Kuroshitsuji unique plotline, interesting characters, mysterious motivations. Plus, just about every time you think it can't get better, it does. Especially recently - there have been so many surprises! As far as genre goes, how about Other.

Rurouni Kenshin because it's a classic everything for everyone

Romance: Fruits Basket because all the characters pasts' are complicated and intertwined and there is always more to someone than at first meets the eye.

Psych: Liar Game because the puzzles and strategies are really well thought out and they keep you guessing.

Shingetsutan Tsukihime is definitely a masterpiece. It's my favorite of all time. (Don't really know what category to put it in. It's got everything)
I nominate InuYasha for an adventure masterpiece, it's a classic everyone should read.
Hoshi no Samidare for action.
I'd nominate Zippy Ziggy for comedy.
More of my favorites include Yumekui Merry (action) and Ikoku Meiro no Croisee (historical/ slice of life)

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Being alone is only lonely if you want it to be.
Staying in lucid delusion for an eternity.

Realism is a big plus for me. It doesn't have to (have) happen(ed) in real life, but it should at least be realistic (could have happened like that).

Besides those below, I haven't read many manga I would call a 'masterpiece'... Or I've long since forgotten them

Slice of Life
Yotsubato! - Because it's fun, light, for all ages, and has very recognisable adventures of a young child and the people around her. Without the need of resorting to fanservice/ecchi or unrealistic events (i.e. supernatural)

Historical
Historie - Solid story with some action but without overdoing it. (though I'm starting to lose interest due to slow releases and lack of progress). Art can be a bit simple at times.
Vinland Saga - Good action oriented story with really great character development and good story progression.

Other
Maybe also Slice of Life, though not the typical life.
IS - Otoko demo Onna demo Nai Sei - Just wow (skip the first volume). Not entirely true to facts but inspiring nonetheless. Again, great character development and the story actually goes somewhere. Realistic manga about not 'fitting in' without the angst and much empathy, informs readers without making judgements or taking sides (though it's hard not to root for Haru and the other mains).
The 'IS' bit can easily be replaced by i.e. being 'gay' or having gender confusion...
Hint: Don't even bother with the live-action, it doesn't even compare with the original.

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Who they, what are, and why?
- Manga Cover Database -

Helter Skelter - For psychological. I thought it was a quite thought-provoking and an interesting way of questioning society's current views on body image. Not for everyone though - the art takes a bit of getting used to.

Shiki - For mystery. I haven't come across another manga quite like it - good for those who are sick of loving vampires haha.

(I wasn't really sure what to categorise these as)
Gokusen (Josei) - I thought this manga was hilarious, not your average delinquent manga.

Paradise Kiss (Josei) - I thought this manga was fantastic: funny, but at the same time highlighting how bittersweet love can be. It was one of my first Josei manga, and after reading it I was really drawn to the genre.

I also second Tokyo Crazy Paradise, Orange Marmalade, Fruits Basket and Liar Game.

Last edited by GunslngrGal92 at 3:36 pm, Sep 29 2011

+ Kiseijuu (Parasyte) - one of my favorite shounens
+ Historie <3
+ Vinland Saga - great action, interesting story
+ Shingetsutan Tsukihime --maybe it should go into action?

Mushishi - not sure what category, but I love this manga. Adventure? Psychological?...It's such a beautiful manga and makes me think of how sometimes even the small things are truly magnificent.

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Second Girl Friends

Nominate Ichigo 100% for harem.

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"I'll shut your mouth~~~~~ with mine~~~"

二息歩行

The title of "king of harem manga" has to go to To Love-Ru and To Love-Ru Darkness though xD

________________
Being alone is only lonely if you want it to be.
Staying in lucid delusion for an eternity.

Rurouni Kenshin, Berserk, Fullmetal Alchemist, and Slam Dunk all deserve to be there. Monster, is better as a mystery than an action series but it's still an excellent series.

I recommend Real for Sports.
Oyasumi Punpun for Psychological.
Yotsubato! for Slice of Life.
One Piece for Adventure.
My Lovely Ghost Kana for Romance.

There should also be categories for harems, comedy, drama and fantasy.

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Mystery:Umineko no Naku koro ni for it's amazing story. (Warning: you will be required to think.)

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Alice came to a fork in the road.
"Which road do I take?" she asked.
"Where do you want to go?" responded the Cheshire cat.
"I don't know," Alice answered.
"Then," said the cat, "it doesn't matter."
~Lewis Carroll, Alice in Wonderland

Hmmm.... I'd nominate

Basara-Action/Adventure
Kanata Kara-Another Action/Adventure w/ cute romance
Cat Street-Slice of Life
Kimi wa Pet-Another Slice of Life
Mademoiselle Butterfly-Historical/Romance (It was so beautiful it made me cry)

Cardcaptor Sakura for shojo/ magical girl

Gunslinger Girl for tragedy

"Bungaku Shoujo" to Shi ni Tagari no Douke A beautifully drawn literature, this manga is a combination of drama, slice of life and psychological. I'm not sure which category fit for this one tough.

I also support Rurouni Kenshin, Slam Dunk and Full Metal Alchemist

Last edited by Sorcha at 2:14 am, Oct 3 2011

you guys cool with not listing those with a bayesian average of below a 8.5 unless special circumstances warrant it?

Now that it has been posted, I will second [m]Once Piece[/m], although it hasn't even finished yet.

The previous two manga I chose Girl Friends and Ichigo 100%, I now nominate them again for BEST SCHOOL LIFE.

________________
"I'll shut your mouth~~~~~ with mine~~~"

二息歩行

^updated. Thanks for the input