Iya Iya En is a new kind of long story for young children which describes realistic children, not idealistic innocent ones. Nakagawa (1935 -) used to work at a nursery school. She wrote the stories in this book to be read to children there. The stories are based on child psychology and reflect the everyday life at a nursery school. Six out of the seven stories were first appeared in Itadori, a coterie magazine; three years later, they were re-written and another story, "Yama no Kogu-chan" [A Boy Bear in the Mountain] was added, and published in this edition.
  The protagonist is Shigeru, a four-year-old boy who goes to nursery school. He often breaks the rules of the nursery school, which are as many as 70. In "Chûrippu Hoikuen" [Tulip Nursery School], he yearns to be in the Hoshi Gumi [Class of Star], the eldest class. In "Kujiratori" [Whale Hunting], he and his friends go whale hunting with a boat made of building blocks. In "Chiko-chan" [A Little Girl Named Chiko], as he climbs on top of a desk after a girl, he is forced to imitate her the rest of the day. In "Yama no Kogu-chan," a real boy bear comes to Shigeru's class. In "Ôkami" [A Wolf], a wolf who tries to catch and eat Shigeru is caught. In "Yamanobori" [Going up a Hill], Shigeru breaks his promise, and the story begins. In "Iya Iya En," Shigeru hates everything in Chûrippu Hoikuen and goes to Iya Iya En. He acts as he likes there, but he realizes he prefers Chûrippu Hoikuen to Iya Iya En.
  Some stories contained in Iya Iya En first appeared in Itadori in 1959. Inui Tomiko praised this work writing that it is free from sentimentalism and amusingly describes children's behavior and mind. On the cover of this edition, Ishii Momoko said that Iya Iya En has surprising power to attract child readers. She regarded Nakagawa as the first Japanese author who can describe the world of children in expressions easily understood by young readers. Some other critic said the combination of everyday life and fantasy is wonderful, while another regarded this book as a kind of observation.
  Iya Iya En was welcomed in kindergartens and nursery schools all over Japan. In 1963, it received the NHK Award for Children's Literature, the Sankei Award for Children's Books and Publications, and the Award for Cultural Material of Child Welfare, and became the Noma Award for Juvenile Literature Honor Book.
  This edition was reprinted more than 100 times in 40 years. Illustrations by Nakagawa's sister, Ômura Yuriko, lively depict the characters.
  In 2001, Miayazaki Hayao's Studio Ghibli made "Kujiratori" into a sixteen minute animation movie.