He is one of the three Heavens Arena fighters who wanted to challenge Gon and Killua for easy wins. He appears to be mean and will do everything in order to become a Floor Master. In the past, he has reached the 200th floor as a rookie without the use of Nen, later was "initiated" after being attacked with a malicious aura attack and lost his left arm.
One of Sadaso's dirty tricks was to kidnap Zushi with his Nen hand to threaten Gon to join a match with him. However, Killua learns of the fight between the two and makes a threat against Sadaso's life, frightening him enough to leave Heavens Arena for good. It still remains unknown whether if Sadaso wears a mask or not, which is commented by a ticket seller when he was talking to Killua. When he leaves Heaven's Arena after Killua's threat, he is wearing sunglasses for the first time and his face looks less pale than before. At this point, when he is leaving Heavens Arena, he calls Gido to warn them that Killua will come after them next.
