Maimaimaigoen is a multidimensional story about the "growing pains of the heart" of 16 children and their nursery school teachers. It examines each person as an individual and accompanies them through the difficulties of living in today's world.

Yu Okada, a new nursery school teacher, is on a field trip to Sanrio Puroland with the kids. As they're about to head home after a fun day, his vision suddenly gets distorted... They wander into the deserted amusement park "Yuropia" where they're confronted by a cute but creepy creature called "Froggy Egg." In order to return to their own world, they must challenge the park's attractions and collect 10 "medals"...