Saeko's Little Sister is a Private Eye A Passionate Lady's Big Secret (Part Two) - S1.E42

Reika explains to Ryo about how a corrupt police officer is interfering with narcotics investigations, and how her former partner was killed by the Yakuza and her desire to clear his name. This leads to a showdown against an expert marksman and also lands Ryo, Kaori, and Reika in Jail after being set up by the corrupt police officer.