MYTHOS is a high-energy instrumental collaboration track built around a fusion of techno, classical piano, and live violin. Composed by Cranky (Hiroshi Watanabe), the piece features two high-profile instrumentalists from the Nico Nico Douga scene: pianist marasy, known for his virtuosic "played it" performance videos and later work as a VocaloP, and violinist Teppei-sensei (Okada Teppei), a soloist who has performed with the Tokyo Philharmonic and Nagoya Philharmonic orchestras. The jacket and in-game movie were created by OTAS. The song was commissioned for SEGA's Tokyo Joypolis digital-ride attraction HALFPIPE TOKYO and was simultaneously added to maimai GreeN PLUS on April 10, 2014. Its title derives from the Greek word "mythos" (μῦθος), meaning a traditional story, legend, or myth, fitting for a track that opens with an authoritative spoken-word passage before erupting into a dramatic blend of synthesized beats, piano runs, and soaring violin lines. In maimai, MYTHOS debuted as a limited unlock requiring 30,000 maimile. It transitioned to a 30 music ticket unlock in maimai ORANGE and became freely available by default starting with maimai ORANGE PLUS. Over successive version updates, the chart levels have been revised multiple times, with the Master chart eventually rising to level 14, a demanding arrangement known for its dense Tap patterns and wide Slide formations, designed by the veteran charter mai-Star. The Expert chart, jointly credited to Jack and 譜面-100号 (and earlier to the pseudonym "合作だよ", meaning "it's a collaboration"), also saw significant level inflation across versions.