4s4ki (pronounced Ah-sah-kee) is a new generation artist who is introducing new alternative pop music from Tokyo to the world. She is capable of writing, composing, and arranging music, as well as making tracks using DTM, and playing the piano all by herself.  Her lyrics, which could be called a "record of self-love," spinning anguish, sorrow, and joy in words that are sometimes raw and realistic, are gaining sympathy mainly from people in their teens and twenties.

     In April 2021, she made her major label debut with Victor Entertainment’s imprint, Speedstar Records, dropping a new single consecutively for three months each featuring an overseas guest act before releasing her debut album Castle in Madness in July.  In August 2021, she played the Fuji Rock Festival, one of Japan’s largest outdoor music festivals.  In December, along with the release of an EP, she held her first tour "HYPER NEW-PUNK LAND" in Tokyo, Nagoya, and Osaka.  She played SXSW 2022 held in Austin, Texas by participating online.  Her album Killer in Neverland in 2022 was extensively featured with an interview on Pitchfork, one of the world’s most prominent online music publications, and the song "Punish" made the site's year-end "The 100 Best Songs of 2022".

     In 2023, 4s4ki launched a collaboration with the globally popular animation Code Geass: Lelouch of the Rebellion and released an “inspired-by” album CODE GE4SS (read: Code Geass) in July.  In September, she appeared in a new commercial for Monster Hunter Now, a smartphone game application that is a live action version of the popular Monster Hunter game, as well as participating in the music for it.  4s4ki is one of the hottest female artists of the 2020s.