Mitsuki was one of Kiyone's classmates back when she was at the academy. She and Kiyone always had a very similar career. Kiyone and Mitsuki were close friends. However, after graduation they went their separate way. Mitsuki went on to have a successful career, while Kiyone got teamed up with Mihoshi and went on to a not as successful career.

Mitsuki quickly rose up the cooperate ladder at the Galaxy Police. Soon she was no longer doing detective work and was assigned to a job at headquarters paying a pretty good salary.

When Kiyone returned to headquarters when she was up for a promotion she ran into Kiyone in one of the halls. The two girls caught up on each other's lives and Kiyone was disappointed to learn that her friend had gone so far, while she spent the past few years in a rut with Mihoshi. Mitsuki knew some of what Kiyone had been doing but nothing for sure.

When Mihoshi stumbled upon the plot that was amiss at Headquarters Mitsuki was ordered to capture Kiyone and Mihoshi. Kiyone escaped. During the last episode when they tell you what happened. Both Kiyone and Mihoshi received promotions to the point at which Mitsuki was reduced to be a lower rank than Mihoshi and Kiyone. They madder her make them tea to get back at her for the way she treated them when they were "Wanted Criminals".