Sakyou is the owner and leader of Team Toguro in the Dark Tournament. He is an extremely wealthy individual, having amassed his fortune through a lifetime of gambling. Sakyou typically presents himself as calm, composed, and highly intelligent, though he harbors a malevolent side that subtly influences his outward demeanor. Despite making only a few appearances during both the Rescue Yukina arcs and the Dark Tournament Saga, Sakyou was the true antagonist behind the scenes, manipulating Team Toguro as his personal pawns, though this seems to have gone unnoticed by the other characters.
Originally one of five siblings, Sakyou diverged from the path taken by his brothers and sisters. While they pursued careers as civil servants, he gradually descended into mental instability and developed a morbid fascination with blood. Over three years, his experiments escalated from dissecting frogs and fish to cats and dogs, eventually culminating in human dissections. He later ventured into the gambling world, employing a unique strategy where he would wager his life to intimidate his opponents. Most competitors backed out when they realized his seriousness, but this tactic was tested five times. One such instance involved the Black Book Club (BBC), of which he was a former member. The last time he risked his life was during the final rounds of the Dark Tournament. It was during his gambling career that he joined the BBC.
At some point during his membership in the BBC, Shinobu Sensui, a former Spirit Detective, witnessed an experiment conducted by the club, including Sakyou. The experiment involved humans slaughtering demons brought through a portal between the human and demon worlds, followed by bathing in their blood. Enraged by this, Sensui killed all the humans involved and began questioning the nature of humanity.
