Tomoko Kawase first rose to prominence as the vocalist and lyricist for the cult Japanese alternative rock act the Brilliant Green, which she was invited to join in 1995 after impressing the bandmembers with her singing at an amateur vocal contest. After the Brilliant Green were suspended in 2002, Kawase concentrated on her twin solo projects, Tommy February6 and Tommy Heavenly6, the first (dubbed after her nickname and birth date) sporting a retro '80s pop sound, and the second plying punk/alt-rock wares. In fact, Tommy February6 debuted before the Brilliant Green went on a hiatus, initially meant only as a little side experiment. However, the "cute geeky girl" image and the synth pop sound caught on, and before long the debut single "Everyday at the Bus Stop" (2001) was followed by three more singles and the eponymous debut album, out, naturally, on February 6 in 2002.
Frankie Valli's "Can't Take My Eyes Off of You" found on the album was featured in a Daihatsu car commercial, adding to the project's success. Tommy February6 also did a photo book, but that was meant to be the end of it, as she returned to the Brilliant Green and worked on other projects -- in 2002, she provided the voice for a character in the anime series Piroppo. However, the Brilliant Green soon folded, and Kawase, who married band mastermind Shunsaku Okuda the same year, returned to solo work. She tried her hand at producing, working with Hinoi Asuka, Speed, and Tommy Angels, but still resurrected Tommy February6 as well. "Je T'aime Je T'aime" came out in 2003, followed by two more singles and eventually the second album, Tommy Airline (2004).
However, Kawase was growing dissatisfied with the character development of Tommy February6, which, according to her, couldn't maintain its purity, and created another alter ego, Tommy Heavenly6, meant to pose as a rebellious but pure girl. Debuting in 2003 with the single "Wait Till I Can Dream" paired with TF6's "Love Is Forever," it was also supposed to be a one-time project, but stuck around. Tommy Heavenly6 did another single, "Hey My Friend," in 2004, the title song and the B-side "Roller Coaster Ride" both featured in the movie Shimotsuma Monogatari, and in 2005 she provided the tune "Gimme All of Your Love!!" for a tribute album dedicated to the Nana manga series and released an eponymous debut album. Tommy February6 also returned in 2005 with the single "Lonely in Gorgeous," used in the Paradise Kiss anime series, but the rock incarnation of Kawase was taking over at the time: even the promo video of "Lonely in Gorgeous" was inspired by the Beastie Boys' "Sabotage," and after its release the synth pop project was put on hold.
Tommy Heavenly6 released three singles in 2006, with one, "Pray," featured in the Gintama anime. The second full-length by Tommy Heavenly6, Heavy Starry Heavenly, arrived in 2007, followed by an extensive tour with some guest appearances by members of the Brilliant Green, who briefly reunited later that year for a tour and some singles. That didn't disrupt Kawase's solo career, as Tommy Heavenly6 released the singles "Heavy Starry Chain" in 2007, "Papermoon" in 2008 (used in the Soul Eater anime), and "Unlimited Sky" in 2009 (featured in Gundam 00). In 2009, she also put out a pair of best-of collections -- Strawberry Cream Soda Pop Daydream for Tommy February6 and Gothic Melting Ice Cream's Darkness Nightmare for Tommy Heavenly6. The Tommy Heavenly6 quasi-concept album I Kill My Heart came out in 2009 as well, charting at number nine.