Studies of childhood in Japan frequently neglect to engage with the texts and images that young people produced, focusing instead on the adult imagination of youth. By looking solely at adults’ conceptions, we miss the importance of other children in forming their peers’ subjectivity. By analyzing the diaries, letters, postcards, yosegaki, and artwork of evacuated children during World War II, this article shows how adults framed the process of language acquisition, but also that children contributed to the creation of a shared language for describing their experiences. When children combined language learning with group experience, which was inscribed through collective writing practices, evacuees came to embrace a strong group identity. Grasping the relationship between collective experience, life-writing, and children’s culture is crucial to understanding how children perceived their world. Apart from these methodological considerations, dismissing the documents left behind by evacuees as mere recapitulations of adult discourse does the history of childhood a great disservice.