Ragnarok is an instrumental composition by sky_delta, a track maker and DJ affiliated with Attack The Music and one half of the unit Endorfin. with vocalist 藍月なくる. The track was contributed to maimai as an original song, arriving in the MiLK PLUS update on September 18, 2018 as a Challenge Track, the second such challenge in that version. With a driving BPM of 184 and a runtime of 2:01, Ragnarok delivers a high-energy electronic sound that builds an escalating sense of urgency, matching its Norse-apocalypse title. The song's MASTER chart, designed by 華火職人 (Kanon Oguni) at level 14 (constant 14.1), is dense with 591 Tap notes and 55 Break notes, making it one of the more demanding charts of its era. The EXPERT chart (level 12+, constant 12.7), designed by LabiLabi, features an 86-slide-note layout. The music video was created by karekitsune. After its two-week Challenge Track window ended on October 1, 2018, Ragnarok became available as a standard unlockable song. Its in-game genre classification shifted across versions, from ORIGINAL & JOYPOLIS in MiLK PLUS through FiNALE, to ORIGINAL in でらっくす, and finally to the maimai category from でらっくす PLUS onward.