Mimi is a young girl who lives with her father and her best friend, a Jigglypuff. Ever since the death of her mother, she has been left home alone with Jigglypuff often. She believes that Clefairy come from outer space and is constantly researching UFOs and the Clefairy species.
Late one night, she is outside with her Jigglypuff when she sees a mysterious UFO land. When she runs over to the scene, she sees many Clefairy, who run away before she can introduce herself to them. Later, they break into her house to steal food, but she gladly offers them snacks for free. In exchange, she wishes they could take her up to see the stars so that she may visit her deceased mother, who she is told has become a star in Heaven.
When Jessie and James of Team Rocket break into her home to steal the Clefairy, she stalls them long enough so that they could not get away before Ash, Professor Oak and Professor Orville could arrive. In the commotion caused by Team Rocket, the Clefairy leave while Mimi and the others are asleep (due to Jigglypuff's Sing), but Ash assures her that the Clefairy will return to visit her one day.
Jigglypuff is Mimi's only known Pokémon. It became her best friend ever since her mother passed away.
All her life, Mimi was very interested in Clefairy. She befriended them by giving them snacks even though they took food from her. Mimi protected the Clefairy from Team Rocket when they tried to steal them. When the Clefairy left, Mimi promises to see them again someday.