Chapter 1 is told from the perspective of middle school science teacher Yūko Moriguchi. She addresses her class at the end of the school year, about one month after the death of her daughter, Manami. She encourages the students to finish their milk, noting that “Milk Time,” a government program to promote dairy products, will not be required in the new school year. Moriguchi announces that she will not be returning next year, confirming that her decision to stop teaching is due to “what happened.”

Moriguchi recounts that she became a teacher because it was the only career she could afford. At a previous school, she met her ex-fiancé, Masayoshi Sakuranomi. He had been a gang leader by middle school and experienced a wild and violent youth, but he later became a lauded teacher who felt that any student, no matter how troubled, could be rehabilitated. During their engagement, with Moriguchi already pregnant, Sakuranomi’s doctor diagnosed him with AIDS; they decided to end their engagement, fearing that the stigma of having a parent with AIDS would be greater than that of a single-parent home. Due to limited childcare options, Moriguchi sometimes brought Manami to school with her.