As World War II draws to a close, 14-year-old Seita and his younger sister Setsuko lose their mother in a devastating air raid in Kobe, Japan. Following a dispute with their aunt, the siblings take refuge in a deserted bomb shelter. With no family left and their food supplies running low, Seita and Setsuko face the harsh realities of survival in a war-torn landscape, relying on each other as they navigate their devastating circumstances.