In Poland, despite the fact that Japanese literature is very thoroughly researched, described and translated, the section of literature dedicated to children (jidōbungaku), for years remained neglected and marginalized. As a result, it is an area completely undiscovered and unexplored. At the beginning of the article, the key role of education and its development in modernizing Japan is presented. Then, the literature of the first twenty years of the Meiji period (1868–1888) is outlined together with introduction of main mass-published magazines on children’s literature. Among them, it was the periodical “Shōnen sekai” that played an epochal role, so its activity and involvement in shaping the children’s literature of the Meiji period are discussed in detail. In the following chapters, the silhouette of Iwaya Sazanami is presented together with his representative work – a fairy tale (otogibanashi) entitled Koganemaru (boy’s name). This is because Koganemaru is considered the most important turning point in the difficult course of systematising children’s literature in modernizing Japan. This article, probably innovative, by examining the beginnings and the process of almost 40 years of emerging of Japanese children’s literature, will fill an important gap in the study of Japanese literature in Poland and maybe become an essential starting point for its development.