Twe'lv is a Japanese music unit primarily known for their connection to the Inazuma Eleven anime franchise. The group was formed with the specific purpose of contributing to the soundtrack of the Inazuma Eleven media project, which began as a Nintendo DS role-playing game before expanding into a television anime series that started airing in October 2008.

Twe'lv consisted of three female members whose names correspond to characters from the Inazuma Eleven story. The members were Haruna Otonashi, aged 16 at the time of the group's formation; Natsumi Kaminarimon, aged 19; and Aki Kino, aged 14. Within the Inazuma Eleven narrative, these characters serve different roles: Haruna is a school reporter, Natsumi is a high-status fan with a tsundere personality, and Aki is the team manager. This integration of performers with their fictional counterparts follows a pattern seen in other anime-related music projects, similar to how Buono! was connected to Shugo Chara.

The group's debut and most recognized single is Seishun Oden, which served as the first ending theme for the Inazuma Eleven anime. The song was released as a single on October 29, 2008. The television-size version of the song has a duration of one minute and thirty seconds, while the full version runs for three minutes and thirty-one seconds. Seishun Oden features lyrics by Toru Reiku, music composed by Takashi Aoki, and arrangement by Yuichi Takahashi. The song's lyrics playfully describe feelings of love and affection through metaphors involving oden, a traditional Japanese winter dish containing various ingredients such as radish, fish cakes, and beef tendon.

Beyond the single release, Seishun Oden was included on the Inazuma Eleven TV Animation Nekketsu Original Soundtrack Vol. 1, released on September 23, 2009. This two-disc soundtrack compilation gathered theme songs and background music from the anime series, with Twe'lv's track appearing alongside contributions from T-Pistonz+KMC and Berryz Kobo. The soundtrack release included both the full version of Seishun Oden and the anime ending version.

Following their work on Inazuma Eleven, no further releases or anime-related credits from Twe'lv have been documented. The group appears to have been a short-term project created specifically for the franchise, with no subsequent music activity or expansion into other anime works. While the name Twe'lv may resemble that of other artists, including a South Korean R&B singer-songwriter named twlv who began his career in 2017 and a Philadelphia-based rapper, these are entirely separate artists with no connection to the Japanese music unit or anime soundtrack work.