Mimiko has red hair and black eyes. She wears a pink dress and yellow shirt underneath and yellow shoes and white panties.
Mimiko is described as being a sweet little girl that never gets lonely, despite not having any parents.
Mimiko meets Papa Panda when he comes by her house looking for Panny, and she offers him a drink. When he learns that she has no parents, he offers to be her father. One day, they go out with Panny and Panny goes missing, ending up in the river heading towards a waterfall. Papa saves him and Mimiko by closing the floodgate and returns to the zoo with Panny on the condition that they return to Mimiko after the day ends.
Panny is seen when Mimiko returns home after running out to do errands. Because he is asleep when they first meet, he is easily mistaken for a toy until he wakes up. When Papa Panda offers to be her father, Mimiko offers to be Panny’s mother, which makes Panny happy. Panny follows her the next day to school and is mistaken for a toy by Mimiko’s classmates, eventually causing a ruckus in the school kitchen when he wanders off, getting covered in curry. The next day, when they go out, Panny is attacked by a dog owned by one of two boys looking for the pandas and defends himself by picking up the dog and throwing it to the owner, demonstrating strength. He later ends up in the river heading towards a waterfall and is saved by Mimiko and Papa Panda before returning to the zoo on the condition that they return to be with Mimiko after the day ends.
She is seen boarding a train to Nagasaki to attend a memorial service for Mimiko’s grandfather. She tells Mimiko to write to her everyday and is assured by her granddaughter that she will be fine on her own. Based on the second episode, she is aware of Papa Panda and Panny, as she’s reading a letter from Mimiko detailing how things are.