This paper investigates the significance that music and musical ability held for the Japanese-Jesuit ambassadors who toured Portugal, Spain and Italy from 1584-1586. Specifically, I will demonstrate how the Jesuits used music as a critical means to reach and convert the Japanese in the seminarios, enabling them to read, sing, and play Western polyphonic and secular music. The Jesuits’ pedagogical use of music not only functioned as a significant missionary tool to transmit the liturgy, but ultimately, the Japanese converts’ ability to play western keyboard and string instruments and sing Latin polyphony signifies most directly the Jesuit’s success in conversion and enculturation.