Nomico debuted in 2004 as the lead singer of the musical circle LOOPCUBE.[2] They released their debut album, entitled Nomico no Ōzora in 2004.[3]
In 2006, Nomico signed to the Lantis record label—named Mellow Head at the time—and released her debut studio album Nomico no Mi that same year.[4][5] Also in 2006, she made her voice acting debut with the anime series Renkin 3-kyū Magical? Pokān, providing the voices of Keimie, an invisible woman who serves as a chaperone of the protagonists, and a pair of talking rabbits named Jun and Tan.[6][7][8] She performed the song "Shichaimashō" for the series, which served as her debut single.