Aiolos is a driving orchestral-electronic composition by xi, introduced to maimai during the ORANGE PLUS era as part of the JOYPOLIS-linked "3 month BOSS RUSH" event series. The track is widely recognized by the community as a spiritual successor to xi's earlier maimai original Halcyon, a connection the composer and video artist yama_ko have both acknowledged directly. The title refers to Aiolos (Aeolus), the Greek mythological keeper of the winds, who in myth is also the father of Alcyone (Halcyon), reinforcing the thematic link between the two songs. At 205 BPM, Aiolos delivers a relentless surge of rapid piano runs, layered synth leads, and dramatic key changes that escalate through its two-minute runtime. The MASTER chart, designed by the charter known as 某S氏, clocks in at 1,100 notes and served as one of the qualifying-round songs for the second Tenkaichi Otogesai (天下一音ゲ祭) event. Its dense streams, wide-spanning patterns, and a particularly taxing piano-solo section that demands precise left-right coordination have cemented its reputation as a demanding high-level boss chart. The video, produced by yama_ko, provides a fittingly mythological visual atmosphere. Aiolos also appears in CHUNITHM SUN PLUS and the GROOVE COASTER WAI WAI PARTY!!!! crossover pack, extending its reach beyond maimai.