Born in Tokyo. A singer-songwriter who captivates audiences with a musical foundation rooted in R&B and a singing voice that seamlessly blends sweetness, sorrow, sensuality, and power. Her artist name is derived from "Eir," the goddess of healing in Norse mythology, reflecting her belief that the power of healing also resides in music.

In April 2021, she made her major-label debut with "Koko de Iki wo Shite", the ending theme song for the TV anime Tokyo Revengers. Later, her song "Finale.", the theme song for the anime film The Tunnel to Summer, the Exit of Goodbyes, became a major hit, particularly in South Korea and Taiwan. Furthermore, she provided the theme and insert songs for both Seasons 1 and 2 of the highly talked-about reality dating show Love Transit. She continued this role for Season 3, which began streaming in October 2025, where the theme song "Last Scene." became a smash hit. She has also performed theme songs for various other works, including the ending theme for the TV anime Togen Anki (Nerima Arc / Second Cour) and the opening theme for the TV anime Reincarnation no Kaben.

Highly acclaimed for her versatile songwriting talent, she has written and composed tracks for numerous prominent artists, including BE:FIRST, Ren Nagase (King & Prince), TAEYEON (ex-Girls' Generation), EXID, WEST., NEWS, and Ryota Katayose. Many musicians have also been drawn to her emotionally expressive vocals, leading to numerous guest appearances on tracks by both domestic and international artists, such as m-flo, SKY-HI, and Pink Sweat$. Additionally, she penned the Japanese lyrics for a popular track by the six-member Korean idol group IVE. She continues to expand her horizons as an artist, also performing as a member of CHIANZ, a four-piece girls' band she formed with her childhood friends.