Sakuragawa is a Forensics officer who works at Shinjuku Station. She knows Yanagi and the others through her friendship with Takeru Sasazuka. Because SRCPO doesn't directly deal with the majority of the X-Day Incidents, Sakuragawa is the main point of contact for the protagonist as she tries to unravel the cases. While Sakuragawa may not seem friendly at first, she warms up to people she likes pretty quickly.
Collar x Malice
Collar × Malice is a visual novel, and follows police officer Ichika Hoshino, who is patrolling Shinjuku, Tokyo. She is attacked, and a collar with poison is placed around her neck; following this, she becomes involved with the "X-Day Incident", which is being investigated by five former police officers.