シックスプラン (Six Plans) is an original maimai song composed by Vocaloid producer 針原翼（はりーP）(HarryP) featuring vocals by はく (Haku). Added to maimai DX BUDDiES on December 22, 2023, the track was made available through the スカイストリートちほー5 (Sky Street Area 5) unlock progression. At a steady 120 BPM, its measured tempo belies the emotional turbulence of the narrative it anchors. The song serves as the musical centerpiece of a pivotal chapter in the Sky Street storyline, which follows the time-traveling protagonists Kohaku and Noah. The accompanying flavor text depicts Kohaku at her lowest point: she has arrived in a future where Akatsuki, the boy she has been trying to save across countless rewritten timelines, is dead, his family line already extinct. The time-travel device C204, a small hourglass whose contents glow and pulse unnaturally, slips from her hand as she questions every choice that led her there. Noah's voice cuts through her spiral, bluntly reframing Akatsuki's deeper motivation: he would defy the gods and tear the world apart rather than let Kohaku die. The narrative frames the song's title as a reference to the branching futures and contingency timelines Kohaku has exhausted in her search for a happy ending, six plans, each one falling short. HarryP (針原翼) is a well-established Vocaloid producer whose discography spans both doujin circle releases and commercial works. His collaboration with vocalist はく, a singer who regularly performs with doujin and Vocaloid-affiliated artists, gives the track a polished and emotionally direct delivery. The song's chord progression and arrangement mirror the story's arc, introspective and weary at the outset, building toward determined resolve as Kohaku picks up the fallen hourglass and refuses to let go.