Born in the South Bay area of Los Angeles, Jennifer Lee's attention turned from classical piano lessons to making left-field recordings with an SP-404 and Fruityloops software. In college, as her love of hip-hop continued to blossom, she signed up for the Beat Cipher, a monthly open-mike night for beatmakers run by Project Blowed. She also frequented the weekly experimental hip-hop event Low End Theory, regarded as the epicenter of the Los Angeles beat scene, and became affiliated with Flying Lotus' Brainfeeder label. Taking her stage name from "Toki," the Korean word for rabbit, and the hyperbolic hip-hop term "monsta," she released the brief, breakbeat-heavy instrumental EP Bedtime Lullabies and mixtape The Attention Deficit in 2008. Her first official releases arrived in 2010, including the EP Cosmic Intoxication on U.K. label Ramp Recordings, and full-length Midnight Menu for Listen Up Records, a subsidiary of the Japanese indie Art Union.
Around this time, Lee was also active in several side projects, making music with a tropical flavor as MAMA TOQUiLLA and electro as TOKiTRON, and collaborating with Suzi Analogue as Analogue Monsta. In 2011, she released the Creature Dreams EP on Brainfeeder, with two songs featuring Gavin Turek, who would soon become one of Lee's most frequent collaborators. Two years later, she returned with Half Shadows on the Ultra label. The album featured guest appearances from rapper Kool Keith and the electronic duo MNDR. In 2014, she launched her own Young Art label with the EP Desiderium. An EP with Turek titled You're Invited appeared in 2015.
In 2016, Lee issued FOVERE, featuring guests like Anderson .Paak, Jonny Pierce, and Kiya Lacey. That same year, she was diagnosed with Moyamoya syndrome, which resulted in a loss of language and the ability to process sound. A pair of brain surgeries helped save the musician, and she quickly returned with the release of Lune Rouge in 2017. The full-length included appearances by Selah Sue, MNDR, Isaiah Rashad, Joey Purp, Yuna, and more. A year after its release, Lune Rouge was nominated for Best Dance/Electronic Album at the 61st Annual Grammy Awards. Lee continued issuing singles leading up to her 2020 full-length Oasis Nocturno, which included guest appearances by Bibi Bourelly, EARTHGANG, and more. Several non-album singles, including "Naked" with Channel Tres and "Say Yes" with VanJess, arrived in August 2021. ~ Jason Lymangrover & Paul Simpson, Rovi