Mimi The Marvelous is a character and an NPC That makes her first appearance in Nations:Chapter 2.
She also appears in Chapter 3, 4 and 5.
Mimi The Marvelous is also the reincarnation of the god Osamodas as she mentioned in Chapter 2.
Mimi's appearance in Nations: Chapter 2
Mimi's first appearance was in Opaket, she was escaping from Team Missile as shown in the cutscene because they want her Ocarina but the player saves her from Team Missile's clutches. And as a reward she gave them Bovis the rockwooled's wool in order to complete their quest.
She also was able to capture Bovis the rockwooled and named him "Bovie" but then she released him as she mentioned in chapter 3.
Mimi's appearance in Nations: Chapter 3
Mimi eventually met the player when they were in Bonta's old stadium. She wanted to find one of her ancestors as she mentioned. At that time she allowed the player to ask her some questions such as her real name, where she got her outfit...
In battles, Mimi was able to deal more damage and heal the player.