Born in Kagoshima City, Kagoshima.
Prefecture, he has roots in Japan, the United States, Germany, and the Philippines and was raised in his early childhood by grandparents who loved music. Influenced by them, he grew up familiar with oldies classics by the likes of Sinatra and Presley, as well as kayōkyoku sung by Showa-era stars such as Yūjirō Ishihara.

In the third year of junior high school, he passed the audition for "NHK Nodo Jiman," which his mother had applied for, and passionately sang Kiyohiko Ozaki's "Mata Au Hi Made." Receiving three bells became a turning point in his life, and he gradually came to aspire to become a singer.

Upon graduating from high school, he entered the Faculty of Music at Tokyo University of the Arts.
At university, he studied vocal technique and musicianship, and while still enrolled, he was scouted by his current agency as a classical crossover singer.

In April 2025, while still a student at Tokyo University of the Arts, he debuted as the lead vocalist of the three-member vocal group IL BUONO. Just ten months after the group's formation, a member withdrew. Facing the crisis of the group's disbandment, he nevertheless carried on the group name and continued his musical activities as a solo artist.

In July 2026, with a concert in Kagoshima the place where he was born and raisedas the catalyst, he resolved to become a singer under his real name, Yu Kawauchi.Yu Kawauchi will share with the world the next generation of classical crossover: “ACC - Asian Classical Crossover.”His singing style is a fusion of classical vocal technique and the delicate, breathy expressiveness found in Asian vocal traditions, creating a distinctive musical worldview in which classical expanse is layered over gentle-toned pop, inviting all who listen into a world of nostalgia.