Miiko is the protagonist of the series. She is an energetic fifth-grader and can be mistaken for a kindergartner due to her height. Miiko loves eating, which becomes a problem because she gets fat easily (as shown in many of the episodes). Her best friends are Mari Shimura (Mari-Chan) and Yuuko Ogawa. She's often found hanging out with her friends or fighting with a boy called Tappei who seems to like Miiko a bit, but is too shy to say it to her himself. He calls her names instead and sometimes gets on Miiko's nerves.