The story begins during the Sengoku period. Four young shinobi - Itō Mancio, Chijiwa Miguel, Nakaura Julião and Hara Martinão - have completed their training.

Far away, in Europe, the people are plagued by devils (diablo) and need help.

Together with their mentor Father Valignano, Julião's sister Shun, and Miguel's pet owl Izayoi, the boys set out on their long and dangerous journey to Europe.