During her second year of middle school, Sayumi started composing music. In 2012, she won the Grand Prix in the finals of the 5th Music Revolution competition, which was sponsored by Yamaha Music. Her first solo concert took place in March 2015 at Tsutaya O-nest in Tokyo. Later that same year, Sayumi made her major debut at the age of 19, performing the ending theme song for Ranpo Kitan Game of Laplace.