Mitsuki is a minor character in Tenchi Universe, appearing only in the episodes No Need for an Escape and No Need for a Conclusion. She is a Galaxy Police officer and a former classmate of Kiyone Makibi. Mitsuki runs into Kiyone inside Galaxy Police Headquarters while the latter is paying paying a visit to her superior officer. Later, under the orders of said officer and a Juraian representative, Mitsuki leads a squadron of Galaxy Police officers in a failed attempt to arrest Kiyone.
Biography
While getting something from a vending machine, Mitsuki notices Kiyone walking past her while she's on her way to the office of the detective sergeant. They immediately have a conversation and catch up, but to Kiyone's annoyance, Mitsuki informs her that many of their old colleagues have been promoted to high positions in the Galaxy Police. Of course, this includes Mitsuki herself, who is now in the "Special Investigation Unit". After Kiyone admits that she's assigned to Investigation Unit 9—one tasked with minor, incidental jobs—Mitsuki tells her that she'll have plenty to time to relax and proceeds to leave. However, Kiyone clearly didn't enjoy the conversation as much as Mitsuki did, because as soon as she leaves, Kiyone angrily kicks a garbage bin and calls Mitsuki a "nasty bitch" (or, in the English dub, "nasty, awful, lousy...").
Later, Mitsuki leads a squadron of Galaxy Police officers to arrest Kiyone as per the orders of the detective sergeant and Juraian representative. They are nearly successful, and Mitsuki taunts Kiyone by suggesting that she should've gone to her to help if she had troubles—except if they were financial. However, Mihoshi intervenes by crashing the Yagami through the corridor. While Kiyone escapes onto the Yagami, Mitsuki is nearly caught in crossfire by her fellow officers and is then almost sucked into space before being caught by an emergency wall.
Following Kiyone and Mihoshi's promotions to detective sergeant and chief criminal prevention officer, respectively, Mitsuki becomes their subordinate, though Kiyone is disappointed that the tea Mitsuki serves her is awful. While she is clearly unhappy about the arrangement, all Mitsuki can do is put up a smile and promise to make it better next time.