Yuvie, I've read Sanctuary. It's art is superb on the realistic side, the story is very realistic and basically follows two childhood friends who are trying to make Japan their "Sanctuary", each of them, by different means. One starts a career in politics and the other as an yakuza.
It has a little similarities to Gungrave, with the 2 friends thing, except that both of them are intelligent and into action, when necessary.
If you like realistic manga and are interested in yakuza stories, then it is a title you should give a chance.