Cancer Schiller was the Cancer Saint in the XXI Century. He although control the almost-dead (and dead) people, and have contact with death with death powers, he hates die, and considers to die a weaklings act; for him, only weak people death in battle.
Became a Mass Murder
Schiller was born in a poor country, where various wars ocurred. He almost dead countless times, but, only when he kill another people, he survived. So, he concluded the weak people ever dies and the strong people kill the weaks, so, the strongest men can survives, and he must kill to survive.
He allied with Mars to survive, and believe Mars is the strongest god.
Schiller build a pillar to Mars, to absorb the cosmo of the students of Pallaestra. But, Mars allow Schiller to control the almost-cadavers of Yuna's friends and presumably other students in the Pillar, taking them from there.
In the Cancer Temple, Schiller after play with Yuna and her friends, send she to the Yomotsu. Kouga arrive's there and goes to Yomotsu too. Kouga is possessed by the cosmo of Abzu (is not Abzu; is only his cosmo that possessed Kouga mind) to defeat Schiller, but, Yuna saves him and try defeat Schiller, and throws him in the Death Hole.