Sanctuary

Two "brothers" after bearing witness to the worst of humanity strive to make a difference in the world. Where one of these brothers attempts to ascend to the top of a crime syndicate. Gungrave differs with a lot more action and with both "brothers" apart of the crime syndicate "Millenium". While Sanctuary has more of a psychological battlefield with one "brother" ascending the ranks of the Yakuza and the other striving to become the Prime Minister. If your a fan of the inner workings of a crime syndicate, characters ascending with power and a brotherhood relationship, then trust me you'll love both series. 

Both about the yakuza, Both tackle yakuzas realistically and do not glorify them heavily.