TV-Series
Description
Yaguchi-san founded the Mini-Moni subgroup within Morning Musume in late 2000, establishing its unique concept of featuring members 150 cm or shorter. She selected Ai Kago and Nozomi Tsuji as initial members, later adding Mika Todd to complete the lineup.

She voiced a lively flower shop owner character in the animated series "Mini Moni the TV," who frequently visited the Mini Moni cake shop. This character interacted regularly with the main protagonists and maintained a friendship with Gocchin, a flight attendant known for sharing exaggerated travel stories. This animated role continued her association with the group after her leadership transition.

In the theatrical film "Mini-Moni the Movie: Okashi na Daibōken!," she portrayed the owner of the Minimoni Café, managing Tsuji and Kago as waitresses alongside Mika as the patissier. The film's plot centered on protecting a magical cake recipe, culminating in her character voluntarily leaving the café to care for transformed fairy characters (played by the 4KIDS unit). She passed leadership to Mika and transferred her position to Takahashi Ai, mirroring her real-life departure from the group.

Her voice acting extended to the "Hamtaro" film series, where Mini-Moni members voiced hamster counterparts called "Mini-Hamus," maintaining her connection to children's media alongside the group's projects.

Following her 2003 exit from Mini-Moni, the character did not reappear in subsequent media. Mari Yaguchi herself participated in a 2018 reunion special performing the group's signature song. The 2009 revival unit "Shin Mini-Moni" featured an entirely new lineup without references to the original character.