Sonsi is a rapper born in 2004 and based in Kanoya, Kagoshima. He gained national attention as a finalist on ABEMA’s Rap Star 2025, standing out among more than 6,000 applicants. During the competition, he drew notice for candid storytelling about living with his grandmother, delivering the punchline BBA with a mix of humor and affection that resonated widely. His unfiltered personality and ability to turn everyday realities into sharp, memorable bars quickly set him apart. In February 2026, Sonsi officially debuted with the single "OYJ", produced by Koshy, known for work with Watson and Yuki Chiba. The track introduced his grounded delivery and straightforward lyrical style, balancing vulnerability with confidence. He followed in April 2026 with "Mottainaijan", further showcasing his knack for blending relatable themes with catchy hooks and crisp production.