Sayuri (小百合) is a freelance assassin and the former lover of Zenji Banba.
Not much is known about Sayuri's personal history. The most that is known about her is that a client tasked her in killing Zenji Banba and that she started dating him to get close to him. She even introduced her parents to him and they talked about marriage before Banba found out about her true intentions. For yet unknown reasons, she let him live. Despite all this, Banba and her maintain a casual relationship with Banba occasionally turning to her for help with work.
Sayuri gets the assignment from Banba to assassinate the head of the Kakyu Association, Long Fang Wang. She goes undercover at Club.Eve as a hostess, dressing up in a manner that would appeal to Long Fang's interests. She spends at least a few weeks working there regularly to get close to him enough for Long Fang to invite her over to a hotel. During one of her shifts, Banba arrives at the club as client to check up on her. She later heads to the room Long Fang Wang and Xianming Lin - disguised as the hostess by the name Rinko - were at and changes place with Lin to relieve him of his position.
A few weeks later, she is finally invited to spend time with Long Fang Wang alone in a hotel. She contacts Naoya Nitta and instructs him to reserve a room below the one they would be staying at. She then heads to Long Fang Wang's room and goes through the body examination process. Once she is let in, she poisons him by inflicting small scratches on his skin with poison laced nail extensions in their moment of intimacy. After the deed is completed, she ties curtains together and climbs down the side of the building to the next floor where Nitta is at. Nitta lets her inside and gives her a uniform for the hotel employees to let her slip away before Long Fang Wang's bodyguards discovered the man's body.