WaT (Wentz and Teppei) is a Japanese pop duo composed of singers/songwriters Eiji Wentz and Teppei Koike. They met each other in 2002 and formed WaT, playing live street performances with their guitars. Their debut single, "Boku no Kimochi", was released in 2005. Wentz, who is half German-American and half Japanese, is also a TV personality. Koike is also known as an actor and can play the harmonica. "Boku no Kimochi" reached the second place on the Oricon chart.