Rocky

Mark is a polar bear cub that is the prison pet of inmate Shūji Orinaka. Mark is almost always seen grabbing onto the front of the prisoner's vest, which Orinaka doesn't mind since the bear acts as an additional weight when he is doing his boxing training. There is a deep bond between the two, although Orinaka became annoyed at Mark when the latter's following of him ruined his plan to escape from the prison.