Taichi is an elementary school student living in an unnamed Japanese town in 1945. He leads a group of children: his younger sister Misako and classmates Jirou, Tsuyoshi, and Yoshio. Before the firebombing, he engages in militaristic play reflecting the era's nationalistic indoctrination, contrasting with his sickly friend Haruo, who avoids such games due to frailty and a preference for reading.

The American firebombing raid destroys Taichi's home and school, abruptly ending his childhood. Forced into survival, he and the group resort to begging or stealing food, retreating to a makeshift cave shelter. After becoming orphaned and suffering injuries in subsequent raids, Taichi continues to lead the group despite their desperate circumstances.

As conditions worsen, the children succumb to wounds and malnutrition. Taichi witnesses the death of his sister Misako first, followed by the other members. He becomes the sole survivor. In a near-death hallucination, Taichi experiences a vision where the spirits of his deceased friends reappear. Haruo’s spirit reveals a miraculous "cake tree" growing from a buried baumkuchen, symbolizing hope amidst devastation. This vision culminates in Taichi's own death, marking the end of his journey from playful child to victim of war.