Tatsuya Kitani is a Japanese singer-songwriter, lyricist, composer, and arranger. He was born on February 28, 1996. His musical journey began in elementary school, where he was inspired by the rock band Asian Kung-Fu Generation. He formed a cover band after junior high and started producing original music, discovering his talent in composition. His interest in Vocaloid production also emerged during this period, and he would go on to produce Vocaloid music under the moniker Konnichiwa Tanita-san. In 2011, he formed the band Hitsujinomure Wa Warawanai and later joined the Honeybee Light Music Club. He was also involved with the band Humanic until 2013. In 2014, Tatsuya Kitani stepped into the Vocaloid scene as "Hello Tanita-san" with his debut song "Kujira to Mercury." His first full-length album, He's Watching From the Ceiling, was released in 2016. Kitani played a significant role as a support bassist for Vocaloid producer n-buna and Yorushika, contributing as a composer and musician. He transitioned into the role of singer-songwriter after covering his own Vocaloid song "The Trash Room Sinks into a Rust Color" in 2017. He also formed the group Sajou No Hana in 2018, and released his debut single "Hoshie" that same year. His first album as a singer-songwriter, I Do (Not) Love You, came out on September 26, 2018. The album Seven Girls' H(e)avens (2019) followed shortly afterwards. In 2020, Tatsuya Kitani released his major label debut album Demagog, which reached number 46 on the Japanese charts. This was followed by BIPOLAR (2022) which peaked at number 23. In 2023, he continued building on this momentum with the release of the single "Moonthief," which quickly became one of his most popular tracks.