Kadoya Fuyumi

An officer in Ikuta's 1st Division, strong-willed, but formal and restrained.
She hates Ruka for being so familiar with Ikuta, despite the difference in their ranks and Ruka's station as a lowly sideliner.
Although ordinarily a stickler for the rules, she dives headfirst into regulation-breaking when she suspects that her family may be involved in a case.