Tokoyami was once an assassin for an unspecified Tojo Clan family who became infamous for wearing various masks while on the job to disguise his identity. Unfortunately for him, an imposter framed him for a murder he did not commit by wearing a replica of one of his masks while doing the killing. This murder apparently ruined his reputation within his family and resulted in him being expelled.
Eventually, Tokoyami was approached by the Reapers, who offered him a position within their ranks. Tokoyami agreed and started killing yakuza for the Reapers, using his missions as an opportunity to track down the man who framed him.
After he joins forces with Ibuki and the Honest Living Association, Kiryu is sent to find Tokoyami and convince him to leave the Reapers.
In order to find him, Kiryu gets information from a musician who hangs out in Taihei Boulevard and spies on people from there. Using the information provided by the musician, Kiryu tracks down Tokoyami to West Park, where the hitman approaches Kiryu from behind and threatens him into stopping his search for him. However, Kiryu refuses and when he turns to face the hitman, he is surprised to see that he is not wearing a mask and looks like a common salaryman.
Since Kiryu has seen his face, Tokoyami attacks him but ultimately fails to kill him. After he's defeated, Tokoyami explains that he used to wear masks while on the job, but he's come to realize that dressing up like an average, forgettable-looking salaryman is a far more effective method for going unnoticed and being hard to identify.
Upon Kiryu's insistence, Tokoyami surrenders himself to the HLA and agrees to give civilian life a chance, but refuses to provide information on the Reapers' leaders. As a reward for persuading Tokoyami to leave the Reapers, Kiryu is paid 120,000 yen.