What is your favorite manga?

[ryuuki_fenikkasu]

(I know this is potentially covered in the "favorite anime" thread, but despite what some people believe, they are two different things.)

Now, since that remark is out of the way...

What manga do you love above all else? What manga-ka always gains your attention or captivate you with their art? What series would you be willing to kill for to have continued or completed? What series/creator got you interested in manga in the first place?  

[ryuuki_fenikkasu]

Just realized I never said what mine are...

Two series I absolutely love that are fairly unknown are The Demon Ororon and X-Day.

The more popular series that I consider favorites are: Saiyuki (in all of it's various "seasons"), Fruits Basket, Yami no Matsuei (Descendants of Darkness), and of course my CLAMP collection, with X and Tsubasa being slightly above the rest.