Dove! Fly Up to Heaven!

The conflict between an oni and a tengu over ownership of a valley results in the degradation of villages on the mountains they reside on. A mother of twins is captured by a slave dealer and separated from her children. Matahachi, her husband, has a snake spirit help him raise his children. Not knowing their 'mother's' identity, the twins - Hato ('Dove') and Taka ('Hawk') - grow up to have superhuman ability.