Kotsu and Gomakasu are a monk and hollow respectively, the latter possessing the former during their appearance in the Return From Exile story arc.
Kostu wears monk robes comes with a has a shakujo on his back. He is of an average height, with a bald head and is somewhat chubby.
Kostu has a very sunny disposition often times even when there is no call for it. He is very polite and seems to be rather carefree.
Kotsu is a monk at the Temple of the Great Heart. When Byakuya and Akashi Kuchiki meet him in the living world, he tells them that during the past few weeks a great number of very strong Hollow have been appearing in the area and have massacred all of his brethren. As the last monk he still shows his kindness to his guests and offers to allow them into the temple, but is subsequently overtaken by Gomakasu.
Kotsu states that he is well trained in the art of spiritual seals and in Spirit combat skills, which are demonstrated while he is under the control of Gomakasu.
- Spirit Halt Seal: This seal technique actually disables a spirit completely and forces it to become unconscious, as he does with Byakuya.
- Spirit Wave Blast: is actually a collection of attacks ranging in size from a small orb of energy to an actual wave of energy.
- Shakujutsu: the monk's art of fighting using their Shakujo staff and channeling spiritual energy through it.
- Holy Shield Barrier:a glass-like barrier that glows with energy and deflect all physical attacks.
Once he leaves Kotsu's body behind, Gomakasu is revealed to be a large green skinned brutish looking Adjuchas level hollow with a mask that is reminiscent of a bull's skull. He has large claws and horns, as well as a massive tail.
Like most hollows, Gomakasu is a veangeful spirit, and is completely self interested. He has a hunger for power that cannot seem to be quenched. He is ruthless and will stop it nothing to become stronge.
Little is known about Gomakasu's past or origins. It is only known that when he first arrived at the Temple of the Great heart he was a minor level hollow, but eventually reached the level of Adjuchas, by devouring other Hollows that came and fell into his trap.
Gomakasu doesn't possess any abilities out of the ordinary for a hollow, except that he is able to inhabit the body of a human and take control of it. Notably he also created sustainable Gargantas for other hollow to come to the temple so that he can devour them.