"Southern Cross" is a track by the Japanese indie metal band 403 (よんまるさん), best known outside rhythm games as the soundtrack to み～や's (Miiya) Flash animation "Nightmare City." The band, formed in 2000 around its namesake lead member 403, brought the song to maimai in 2021, a full nine years after the arcade series first launched, marking the band's very first appearance in the franchise. The song originally appeared on 403's 2007 album N.E.W.S. and features vocals by Hatanaka, with lyrics that alternate between crusader imagery and earnest motivational passages ("This little time that you live here may be treasure when you are old"). In maimai, "Southern Cross" spans five DX difficulties up to a Lv.13+ Re:MASTER chart designed by Jack. The Re:MASTER chart is notorious for its relentless tap-heavy endurance, at 1,194 total notes with 1,103 Tap notes, it was briefly the second chart in maimai history to exceed 1,100 Taps (after "PANDORA PARADOXXX") and remains one of the most physically demanding Lv.13+ charts in the game. The MASTER chart, also designed by Jack, incorporates a visual homage to "Nightmare City": toward the end of the final chorus, a series of Slide notes trace the shape of stick figures that featured heavily in the original Flash piece. The EXPERT chart was designed by サファ太 (Safata). "Southern Cross" also crossed over into CHUNITHM VERSE in June 2025, extending its reach beyond the maimai cabinet.