When Midori was about 18 years old, a serial hit-and-runner was stalking the streets, randomly targeting high school girls wearing long skirts, due to the harassment by a girl gang he had suffered under (the girls had been wearing long skirts as well, as a part of their rebellious looks). Midori was also a member of a girl gang, and her best friend ended up the first fatality, so since the culprit had not been caught after a while she decided to help apprehend the killer and volunteered to act as a decoy. There was an apparent shortage of police able to help her, and Midori was extremely stubborn and insisted to be alone; under orders of Commisioner Matsumoto, she was teamed up with Juzo Megure, then still a junior police officer.
Unfortunately, the car runner surprised and hit them both. Megure tried to pull Midori out of danger, but they were still harmed; fortunately, Megure was able to remember the car's license number, and the perpetrator was soon arrested. Midori was gravely injured in the accident, but recovered with only a scar on her forehead to show for her ordeal, and some time afterwards she married Megure out of gratitude. In a strange switch of role, she is perhaps the only person who has managed to temper his impulsive surges, a role her husband feels a bit bashful about.
Midori has also appeared, in an unseen role, as a witness to a crime and had to be taken to the station for questioning, as well as making a cameo appearance during the White Day Murder Case.
She is also mentioned by Takagi in episode 146. She was inside the bank where the robbery happened and was wounded by the criminals who pushed her around. Because of that, Takagi says, Inspector Megure is taking that case very seriously.