Yuki Takajo, known professionally as Leon Niihama, was born on May 11, 1996, in Chiba, Japan. He is a singer specializing in enka and kayōkyoku music. Initially devoted to baseball from an early age, Niihama decided to pursue a career in singing after failing to achieve his dream of playing in the Koshien tournament. Influenced by his father, Yasuo Takajo, who was also an enka singer, Niihama cited Hideki Saijo and Itsuki Hiroshi as major influences. Niihama's music career began on May 1, 2019, with the release of his debut single "Hanasanai Hanasanai" under Kaikyo Record, a subsidiary of B Zone. His television show "Hajimemashite, Boku, Niihama Leon Desu!" aired from 2019 to 2021 on Chiba Television. In the same year, he won the "New Artist Awards" category at the 61st Japan Record Awards. He continued his success by winning Best Enka/Kayokyoku New Artist at the 34th Japan Gold Disc Awards in 2020. His single "Tukamaete Konya" served as the opening theme for the anime television series Case Closed: The Culprit Hanzawa in 2022. Niihama also ventured into acting, making his debut in the television drama Gekoku Juukyuuji in 2023 and released his first video album Leon Niihama 5 Shuunen Kinen Concert. In 2024, he collaborated with guitarist Tak Matsumoto on the covers single "Kizudarake no Roller", included on the kayokyoku covers album The Hit Parade II.