Complete manga to get: Black Cat (20 vol)

You know when you start following a manga, you expect reading it to the end, and it get's frustrating if you read a manga and in one point you find that the company responsible for providing it, get's bankrupt, or get the manga on hiatus, or just like one company we all know *coughTokyo..coughpop.. cough* always does not disappoint us to disappoint us.
well, i thought i would start with a series of recommendations about some of the complete manga you might want to start reading, and some of the manga which is still available.
to start off, we are going with our beloved assassin Train, in the manga Black Cat, you might have watched the anime already, and fell in love with it, but if you haven't read the manga, then oh well, lets say the manga is something else, well, i haven't watched the whole anime yet, but i heard the ending is open, so it's all the same, you need to read this manga either way.
This manga follows the story of Train an assassin known in the underworld as the black cat with the tattoo of number XIII on his neck. train leaving his past as an assassin behind, starts working with Sven to work as sweepers, it's a job smiler to bounty hunters catching wanted criminals and delivering them to justice,But trains past is still hunts him putting train on situations that force him to give the cat eye to his enemies, along the way train and sven meets foes and friends who shape the story for them.
This manga comes from Kentaro Yabuki the one responsible of creating Yamato Gensouki, Mayoi Neko Overrun! and To-LOVE-Ru.
Black cat started in 2000 and finished with total of 20 Vol, published in English by Viz Media.