Music plays an essential role in Christian communities. A number of Japanese converts to Christianity begin to build their faith after they have religious, inner, or physical experiences while reading the Bible or singing a gospel song. In this sound installation, the audience experiences a spatial soundscape of their voices and songs, recorded by a binaural microphone, and made available for listening through headphones, one visitor at a time. Video work presented in complement to the sound installation explores the conversion process of these Japanese “firstfruits” (the first person in a family who converts to Christianity) at German Evangelical and Pentecostal churches, and gospel choir groups. Christians form a super monitory in Japanese society; merely 1% of the Japanese population identify as Christian. The research project focuses on their emotional, inner, and physical experiences — in other words, "Holy Spirit's work" or "guidance of the Lord"— as the seed of their faith. People at German Evangelical churches encounter life altering biblical quotes at a decisive moment in their faith. Attendees at gospel choir and Pentecostal churches cultivate their faith through singing gospel songs, or having a fierce inner experience at gospel workshops or concerts. In using two-years of fieldwork, which included interviewing, participant observation, and video/sound recording, this dissertation investigates how Christian converts experience these special events and how they interpret their experiences after becoming Christian. It does so by analyzing their conversion stories, which they share as "public testimonies" in communities, to affirm their faith.