Kazuha Toyama
Kazuha and Heiji Hattori have been close friends since childhood. Their fathers work together at the Osaka Police station, where Kazuha's father, Ginshiro Toyama is a close friend and partner of Heiji's father, Police Chief Heizo Hattori. Her mother is mentioned in episode 573, where she wanted Heiji to bring Kazuha her drinkbottle.
At one time in their youth, Heiji had had the unfortunate idea of locking themselves together with a set of old hand...