Mitsuki is a Galaxy Police officer in Tenchi Universe. In the Galaxy Police Headquarters, Mitsuki encounters Kiyone, her former classmate, as she is paying a visit to the detective sergeant. Later, under the orders of the detective sergeant and the Juraian representative, Mitsuki leads a squadron of Galaxy Police officers in a failed attempt to arrest Kiyone.
While Kiyone is paying a visit to the detective sergeant on Galaxy Police Headquarters, she walks past Mitsuki, who immediately notices her old classmate and begins a conversation with her. However, 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 list 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 and is tasked with serving both of them tea, something that Kiyone chastises her for being unable to make properly. Though she is clearly unhappy about the arrangement, all Mitsuki can do is put up a smile and promise to make it better next time.