Will-O-The-Wisp

First featured in Pump It Up THE REBIRTH, "Will-O-The-Wisp" stood out for sheer speed. A tempo of 210 BPM was dizzying for the era, and with its dense note design it became the version's boss song. The title nods to the phantom flame folklore later revisited by its remix, Ignis Fatuus. A famous quirk lives in REBIRTH's Division mode, a branching-chart feature: if the player holds only the W arrow for the whole song, they unlock the "All Wild" route, an absurd novelty chart of endless drilling. Pressing the center (G) arrow even once breaks the route and locks you out of it.

The Single spread runs from the beginner S2 and S5 up to the high tier. The S13 was the original hard chart and the heart of the song's boss reputation: at 210 BPM it leans on eighth-note runs with frequent hip twists, and the mid-song burst is a real stamina sink, which is why PHOENIX bumped it to 13. The S16 is the crazy upgrade, similar in places but adding sixteenth-note trills that crater the gauge if you try to slide through them; it climbed from 13 toward 16 across Prime 2, XX, and PHOENIX. The S19, added in NXA, throws sixteenth-note runs and three-note bursts mid-song and sits among the more approachable charts at its level.

Double is just as restless. The D14 began life as a Half-Double, rising from 10 to 13 in XX and again to 14 in PHOENIX. The D16, the original freestyle, demands relentless weight shifts with no breathers and was for years one of the hardest charts in its bracket until PHOENIX settled it at 16. The D20, Prex 3's nightmare, is built around unusual weight-shift movement, with legs stepping backward or driving forward through twists. The D21 unfolds the S19 across two pads with even faster runs. The D25, designed by WINDFORCE and added in XX 2.01, pairs an opening weight-shift section with a brutal closing wall of 210 BPM sixteenths, demanding you reach the final staircase with a full gauge in hand.