Cancer Deathmask (蟹座のデスマスク Kyansā no Desumasuku?) was depicted as a very sadistic and malevolent man who used his power as he wanted without bending to Athena's will. Deathmask covers every inch of his temple with the faces of his fallen victims - warriors and civilian men, women and even innocent children. Deathmask is one the few Saints who knows the truth about the Pope and the Gemini Saint, along with Pisces Aphrodite, but he continues obeying his orders.
He believes that justice is not a real concept and is just a name given to the will of the stronger, since those with power can force their wills on the weak and call it fair. Even after joining sides with Athena, Deathmask remains a diabolic, sadist person, facing Aries Mu and Pegasus Seiya without showing remorse and even attempting to kill the latter. In the US version his name was changed to Mephisto. It is unknown if Deathmask is his real name or a title since he collects the faces of his victims.
As a Gold Saint, Deathmask mastered the 7th sense, hence he can move at the speed of the light. He has shown strong psychic powers, using his telekinetics abilities over a target in China when himself was in Greece. He often uses this power to levitate in the air as well, as shown in his first fight against Dragon Shiryu and when he fought the Giant Kyanos Phlox. So far, he only showed a single special technique:
Praesepe Underworld Waves (積尸気冥界波 SekiShiki Meikai Ha?): Tseih She Ke, pronounced in Japanese as Seki Shi Ki, is the Chinese name for the Beehive Cluster (also know as Praesepe). Deathmask blasts his opponent with a spiral cosmic-wave attack. As a result, his opponent's soul is sent into the Yomotsu Hirasaka, the Japanese gateway to the underworld, a dimension between the world of the living and the world of the dead.
Deathmask himself can freely travel from the living dimension to the Yomotsu Hirasaka without suffering any consequence. However, enemies sent there through the Praesepe Underworld Waves are heavily affected and their bodies loose almost all strength. Normally is impossible to someone's soul to travel back from the Yomotsu Hirasaka, but if someone conduct them from the living dimension, it is possible to follow the path back.
It is implied that, like the other Gold Saints, Deathmask reached the 8th sense at the end of the Hades's saga to be able to regain his will on the underworld and help the other Gold Saints.