Long ago in a faraway eastern land, a horned race of "oni" lived as slaves and playthings under the despotic rule of Momotaro. Only certain oni were allowed to live freely on Onigashima, a secluded island. This was where Akane was born and raised. One day Akane's father, leader of Onigashima, asked her to procure some dumplings. For the first time in her life, Akane left the shelter of Onigashima to visit the mainland. When she saw the suffering of her people, she was outraged. Akane vowed to find and dethrone Momotaro.