Komatsuna Sakato

Hana Kappa, who was always getting scolded by his mom, would join his friends in complaining about his nagging mother. One day, however, a "Butterfly Warrior" arrived in Yamabiko Village, and all the mothers in the village were kidnapped. Hana Kappa and his friends set out on an adventure to rescue the mothers, accompanied by a mysterious boy named Polu, whom they met by chance.

The story is set in a village in the southern Japanese prefecture of Kōchi during World War II. Even in this remote mountainous area, the perception of American and British people as "brutes" has taken root, due to the deaths and injuries among the villagers' relatives. A elementary schoolgirl named Eiko transfers from the city of Yokohama to this village. Eiko happens to have blue eyes from her American father, and her classmates make no attempt to rein in their bullying. Other than Eiko's homeroom teacher Akiko, even the teachers view Eiko the same way that the children do. However, a boy named Kenta views Eiko more with curiosity than with hostility. The children's lives change as the injured father of one of Kenta's classmates returns from the battlefield and news of more casualties arrives in the village.

Jiro, who makes his living hunting beasts, encounters Kuumi, who is on the run, and saves her. As rumors spread regarding humanity and a mysterious experiment, they seek to discover the world’s secrets together.