Mimi is a young girl who lives in Vientown, just next to the Ranger Base. She refers to herself in the third person, rather than I, and she owns four Happiny who get lost sometimes. In a mission in Vien Forest, the player must find the remaining Happiny during the forest fire so that Mimi could leave the forest.
In the Special Mission Recover the Manaphy Egg!, one of her Happiny met a Chansey before the mission and goes off to find spherical objects to replace its stone as it wants to be like the Chansey. Mimi, Luana and the player go all over Vientown to search for this missing Happiny. Eventually, they end up chasing the Happiny to Nabiki Beach where it finds a Manaphy Egg and goes off to Breeze Hill to protect it. Then, the player must chase the Happiny and capture a Pichu and Glameow that are helping to protect the Egg. At the end of the mission, Mimi joins Professor Hastings and all of her Happiny who are carrying the Egg to the Ranger Union.