Growing up Sakyo was a sociopath, as evidenced when he took an after school job in his teenage years and would make a game out of cutting animals hearts out,for the thrill of seeing how long he could keep them alive. Upon reaching adulthood he switched his focus from torture to gambling, which he used to build up his fortune. He eventually moved to more extreme gambling where he began betting on the Younger Toguro in fights to the death after he became a member of the Black Black Club. He and the Black Black Club were later found by Spirit Detective Shinobu Sensui, while they tortured innocent demons to collect their blood, during which Sakyo was the only one to escape death. He remained a member after this with several other members who had not been present for the incident. Following the kidnapping of the ice apparition Yukina, Sakyo participated in the betting against the Toguro Brothers victory against Yusuke and Kuwabara staking his entire fortune on their victory.He proved to be right, although it was revealed the Younger Toguro had faked his own death, for Sakyo's benefit. After the heroes leave, Sakyo has Toguro murder the now penniless Tarukane and agree to Toguro's suggestion of Yusuke and his friend participating in the Dark Tournament.
During the Tournament Sakyo spent most of the time observing from the VIP area alongside the rest of the Tournament Committee,only venturing out to speak with Toguro and to save the life of Shizuru Kuwabara from being killed by a horde of demons. Towards the finals of the Tournament the rest of the Committee begins to question Sakyo's motives, which he reveals his desire to open a tunnel to Spirit World with his tournament winnings to observe how destructive demons could truly be. This frightens even the Committee who prepare to kill him with a group of demons, but are interrupted by Younger Toguro who murders the demons and the Committee. When the finals finally arrive between Team Toguro and Team Urameshi Sakyo is drafted as the fifth member of the team and observes the various battles from ringside. He then makes a deal with Team Urameshi owner Koenma, that neither of the two will fight and the fight between Yusuke and Toguro will be the deciding match with each wagering their life on their fighter. Following the defeat of Toguro, Sakyo resolves to follow through with his deal,despite Koenma offering him to let him out, he simply produces a detonator to cause the stadium's destruction. However during the fifteen minute countdown he talks with Koenma who questions if his experiment to open his portal to would be destroyed, and finally with a distraught Shizuru. With his last actions he gives Shizuru a special lighter, before waiting for the rubble to kill him.