Harumi Kuromura is the young daughter of Keiko Kuromura and niece of Shusaku Hojo. Residing with her mother at the Hojo family home in Kure during World War II after Keiko's return following her husband's death, Harumi develops a close bond with Shusaku’s wife Suzu Hojo when Suzu joins the household. A cheerful child with brown hair and brown eyes, she is often observed drawing pictures or watching naval activities in the harbor. Her personality blends girlish femininity with a tomboyish passion for Japanese warships; she identifies vessels by sight and voices ambitions to become a sailor, interests inspired by her older brother Hisao. Despite wartime hardships, Harumi sustains an upbeat demeanor, becoming a beacon of light for her family.

Her story concludes during a U.S. air raid on Kure in 1945. While walking with Suzu, Harumi encounters a time-delayed bomb. The ensuing explosion kills her instantly and severs Suzu’s right hand. This event deeply scars the family, particularly Keiko, who initially holds Suzu responsible for Harumi’s death. Harumi’s absence creates an enduring void in the household, emblematic of the war’s obliteration of innocence and daily life. Her death catalyzes Suzu’s emotional collapse and serves as a pivotal narrative moment preceding the atomic bombing of Hiroshima. Harumi’s character arc concludes with her demise.