Barabara ~Karisoke Rainbow Rose~ (バラバラ〜仮初レインボーローズ〜) is the official theme song of the Nijisanji YouTube variety program "Nijisanji no B-kyuu Variety (Kari)" (にじさんじのB級バラエティ(仮)). Performed by the show's hosts, VTubers Hanabatake Chaika (花畑チャイカ) and Shiina Yuika (椎名唯華), the track captures the playful, offbeat energy of the series with a buoyant pop melody built around a steady 135 BPM. The song was composed, written, and arranged by OSTER Project, a veteran creator whose work has appeared across the BEMANI series, Touhou arrangement circles, and multiple maimai installments including "Mint Tears" and "Scars of FAUNA." The title is built on layered wordplay: "barabara" simultaneously evokes the Japanese adverb ばらばら ("scattered" or "disorganized") and the kanji 薔薇 (bara, "rose"), linking to the "rainbow rose" motif. The word "karisoke" (仮初, meaning "temporary" or "provisional") directly mirrors the "(仮)" (tentative) appended to the show's name, a self-deprecating nod to its unpolished, improvisational format, wrapped in the contrasting elegance of a rainbow rose. The song's in-game jacket art and unlockable titles further reference the show's branding and catchphrases. In maimai DX, the track arrived on May 24, 2024, as part of the BUDDiES PLUS update with regional availability across Japan, International, USA, and China. The MASTER chart, designed by はっぴー, stands out for its heavy Slide-note emphasis, 80 slides out of 461 total notes, while the EXPERT chart by Luxizhel offers a dense Tap-driven layout at level 10+. A special in-game title linking this song to the earlier Nijisanji collaboration track "うぇいびー" ties the two VTuber crossovers together within the maimai DX title system.