KING is BACK!! is an original song produced for the maimai rhythm game series by the doujin music circle A-One. Composed by ELEMENTAS with lyrics and vocal performance by Takahito "Rute" Koshida alongside aki, the track runs at 176 BPM and was first added to maimai MURASAKi PLUS on September 7, 2017. Its lyrical content revolves around themes of a returning king, high-stakes games of deception, and unveiling hidden cards, the chorus repeatedly chants "KING is BACK!!" as a triumphant declaration, while verses reference poker faces, trades, and the start of a "New Game." The song stands out among A-One's contributions to rhythm games as a maimai-original piece rather than a Touhou arrangement, which the circle is best known for. In-game, KING is BACK!! appears as the opening track of the 白十段 (White 10th Dan) rank course and forms part of a loose thematic trilogy of "BACK"-titled songs alongside Back 2 Back and WE'RE BACK!!, all of which can be chained in a single credit for a special collection title. The Master chart, designed by Revo@LC, packs 1,055 notes across Tap, Hold, Slide, and Break categories, a notably dense layout that has see-sawed between level 13+ and 14 across version updates. Its Expert chart, designed by 某S氏 (Bou S shi), offers a more approachable but still challenging 11+ gate. A later UTAGE (宴) chart was added in maimai DX BUDDiES on February 29, 2024, labeled as a "reverse" (逆) type and credited to the designer under the humorous name "お前がBACKするんかーーーい!!" (a pun on the song's title).