Clover - CLAMP

Kazuhiko is a young, but already deeply wounded black ops agent of a baroque, retro-tech future - pulled out of retirement to escort Sue, a mysterious waif, to a destination she alone knows. Suu and Kazuhiko have never met . . . yet she knows him, having grown up since the age of four with her only human contact being two distant voices: that of her elderly "grandma," General Ko, and of Kazuhiko's dead girlfriend, Oruha. And Suu has been kept in that cage all these years because of what she is, and what the Clover Leaf Project found her to be -- a military top secret, and the most dangerous person in the world.

(Source: Dark Horse Comics)

Clover was first published in English by Tokyopop as individual volumes from May 15, 2001 to March 20, 2002. After Tokyopop became defunct, the license was taken over by Dark Horse, who published the title complete in one omnibus volume on May 13, 2009, as well as digitally on May 21, 2014.