Eunyoung Kim (김은영) is a pianist, composer and improviser based in Seoul whose music moves between carefully written pieces and free improvisation. Her first album as a leader, Silent Child (2018), appeared under the band name The KEY, and her solo piano album Earworm (2020) was the first official release of the Seoul label Mung Music. On June 15, 2024 she played at Cafe OTO in London in a quintet with the cellist Okkyung Lee, the saxophonist John Butcher and the bassist John Edwards, and four days later gave a trio concert at the International Anthony Burgess Foundation in Manchester. She is a different person from the jazz vocalist Woongsan (웅산), whose birth name is also Kim Eun-young. Her own birth year and birthplace have not been published.

Cafe OTO's biography says she built her musical foundation on classical and church music and added jazz during her studies in the United States, where she was exposed to improvised music. The biography on the Bandcamp page for Earworm gives the details: she studied classical violin and piano from an early age, found a talent for jazz piano at 18 while attending Dongduk University in Korea, entered the undergraduate programme at Berklee in 2007 and then won a scholarship to the master's programme at the New England Conservatory in Boston. The American listing site Jazz Is Discovery gives the same Berklee and New England Conservatory outline. She returned to Korea in 2013 and has worked there since as a bandleader and as a sideman.

Her earliest credit on Discogs is A Farewell To An Unknown Friend (Leaplay Music, December 15, 2014), a trio album billed to the saxophonist Sungjae Son (손성제), the drummer Junyoung Song (송준영) and Kim. TenAsia's critic noted that saxophone trios usually leave out the piano, and wrote that here the piano held the harmony and left Son room to play slowly, like painting a winter landscape. The Jazz People editor 김광현, writing the programme note for her 2019 EBS Space Gonggam appearance, said she does not play many notes on that record yet still builds the sound of the group. In February 2016 she played piano on the first track of the singer Jung Mijo's (정미조) comeback album 37년 (JNH Music): the 2016 version of her 1972 song "개여울", which the liner essay describes as a performance for piano and the bass clarinet of Son, who produced the album. Cafe OTO adds that she works as a pianist and arranger with the K-pop musicians Jung Mijo and Parc Jae Jung. In 2016 the Korean magazine Jazz People named her its Rising Star Pianist.

Silent Child was recorded in September 2016 at Yireh Studio by Daesup Shin and released on August 2, 2018. All ten pieces are her own compositions, and the lineup is the trio she called The KEY: Kim on piano (and voice on the last track), the bassist Jaekon Jeon (전제곤) and Song on drums, with the guitarist Jinsoo Kim and the tenor saxophonist Sunjae Lee as guests on the title piece. The Korean release notes say the album gives little weight to improvisation compared with most jazz records: improvised passages were transcribed into notation, the written pieces were then played back as written or used as material for new improvisation, and the cycle continued until the two kinds of music met. Most titles came from images that surfaced after the recording; "Kaaaach-tooey" came from the sight of people spitting in the street, and the three parts of "The Circus" ("Elephant", "Clown" and "Ring of Fire") each carry their own subject. The name The KEY, according to the EBS programme note, is both her initials and a key to music, jazz and life. Pete Rende mixed the album, Nate Wood mastered it and Lee made the cover art.

On March 7, 2019 she shared an EBS Space Gonggam evening with the pianist 최윤화 in the series "2019 New Faces of Korean Jazz", announced with everyone who played on Silent Child; the planned programme included "Free Improvisation", "Spring Break" and "Public Enemy", and EBS posted a video of the programme on YouTube. Later that year she played piano, and arranged one track, on 이상한 꽃 ("Strange Flower", Mirrorball Music, October 29, 2019), the vocalist Jimin Lee's (이지민) album of settings of poems by Yi Sang, with Sunjae Lee and Song again among the players.

Free improvisation moved to the centre of her work in 2020. On January 15 she, Sunjae Lee on saxophone and the New York-based drummer Dayeon Seok recorded one 50-minute improvisation, Pulse Theory, at GhettoAlive in Seoul. On July 12 she recorded Earworm at the Seoul studio BOOMiz: eleven improvised pieces for solo piano, taped on a Tascam 424 cassette recorder in a couple of hours without rehearsal or much editing. Lee, who mixed and mastered it and made the artwork, had founded Mung Music that year as a label for experimental improvised music from Korea; he told PAN M 360 that she was one of the musicians he most wanted to release and called her a genius of jazz piano who deserved to be world famous. The album reached streaming sites and Bandcamp in early August 2020, and Discogs lists a cassette edition of 20 copies released on November 4, 2020. New York Music Daily reviewed it on October 26, 2020, and Cafe OTO says that tracks from the album were played on the BBC Radio programme Freeness. In November 2020 she also played piano on "for Alfred", a track by Alfred Harth and Co on the g-r-a-p-h-i-c project, in which musicians interpret graphic scores by the Belgian musician Dirk Wachtelaer, with Harth on voice and bass clarinet, the drummer Soojin Suh, the guitarist Sang Jun Ahn and Lee on tenor saxophone.

Junyoung Song plays on several of her ensemble records and concerts; in the PAN M 360 interview Lee described him as Kim's husband and as his own closest musical associate in Seoul. In June 2024 Kim and Song joined Okkyung Lee for the final night of the cellist's three-day Cafe OTO residency. In the summer of 2023 Kim had improvised eight pieces on a Prophet Rev2 synthesizer, which she released on her own Bandcamp page as 꿈 비 ("Dream Rain") on February 29, 2024. Cafe OTO's biography also records her appearances as a leader and sideman at the Beijing World Music Week, the Beishan World Music Festival, the Kumamoto Street Art-flex Jazz Festival, the Jarasum Jazz Festival and the JazzKorea Festival.

Her music works on two linked ideas: improvisation turned into notation, and notation turned back into improvisation. The Korean notes to Silent Child describe exactly that loop, and the EBS programme note presents her as a pianist who moves between modern and free playing and carries melodies from improvisation into composition. Earworm shows the other side. The New York Music Daily review calls the eleven untitled pieces unlike anything else, hears in them a blend of twentieth- and twenty-first-century classical music with jazz, and notes themes and variations, close harmonies and a flirtation with twelve-tone writing. The reviewer reaches for several comparisons, track by track: the composer Louis Andriessen if he played jazz, Federico Mompou played far more slowly, the brooding solo piano of Satoko Fujii, a turn toward Thelonious Monk and gospel, and the firm attack of Keith Jarrett in the 1960s. Those are the reviewer's comparisons, not influences she has named; interviews in which she lists her influences are not available.

Her recorded range is wide: written trio music with bass and drums, free sets with saxophone and drums, solo piano improvisation, jazz songs for a singer, arranging for pop musicians and a synthesizer album.