じょいふる is a maimai cover version of the spirited J-POP single by Japanese pop rock band Ikimonogakari (いきものがかり), written by the band's guitarist and primary songwriter Yoshiki Mizuno (水野良樹). The title is a playful phonetic twist on the English word "joyful" (ジョイフル), deliberately spelled in hiragana rather than the usual katakana, a wordplay that the lyrics themselves acknowledge in the line "イッツ ジョイふる" (It's joyful). The song layers bouncing pop melodies with exuberant, nonsensical vocalisations like "ぴぷぺぽ ぱぴぷぺ" and a chant-like "JOY と JOY と JOY と POPなベイベー," creating an atmosphere of unrestrained cheerfulness. One of the original tracks available at maimai's launch on July 11, 2012, じょいふる has undergone several revisions across the game's lifetime. Its genre classification shifted from J-POP (in maimai and maimai PLUS) to POPS (from maimai GreeN onward), and its Master chart, originally a formidable level 10 at launch, was progressively dialled back to level 9 in maimai PLUS and then to its current level 8 from maimai GreeN onward, reflecting the series' evolving difficulty standardisation. An Easy chart (level 2) present in early versions has since been retired. The four remaining Standard charts share brisk 159 BPM energy and a straightforward note structure with no credited designer, a hallmark of maimai's earliest anonymous chart-production era. The cover arrangement faithfully preserves the original's bright, uptempo character while tailoring it for the rhythm game format.