Loveless, Vol. 2: Soul of Chains
Ritsuka, the one known as Loveless, has become a Sacrafice for the powerful Fighter, Soubi. When Soubi fights, Ritsuka is the one who takes all the injuries.  In return, Soubi follows Ritsuka's orders.  But when Ritsuka's one order is not to fight, Soubi takes matters into his own hands.