IDSMILE (アイディスマイル) is a Vocaloid-original song by producer toa (とあ), brought into maimai DX BUDDiES through the game's collaboration with Project Sekai: Colorful Stage! feat. Hatsune Miku. In the Project Sekai universe, the track is performed by the unit 25時、ナイトコードで (Nightcord at 25:00) alongside MEIKO, with vocals from the unit's four members, Mizuki Akiyama, Mafuyu Asahina, Kanade Yoisaki, and Ena Shinonome, layered with MEIKO's voicebank. The title is a portmanteau of "ID" (identity) and "smile," and the lyrics weave themes of self-expression, emotional boundaries, and the fragile connections between people, fitting for a song about maintaining one's identity while reaching out to another. Toa, known for his polished pop-electronic style and earlier viral hits like "与う" and "フラジール," brings his signature glitchy yet melodic sensibility to the track. The 171 BPM arrangement pairs a driving beat with shimmering synthwork and a chorus that builds into an emotionally charged release. In maimai, the Master chart (level 12.8) was designed by りんご Full Set and features a dense 510-note layout with heavy Slide and Touch clusters, while the Expert chart (level 9.6) by Luxizhel offers a more measured introduction to the song's rhythmic structure.