RIFFRAIN is a maimai original song written, composed, arranged, and performed entirely by Japanese singer-songwriter 夏代孝明 (Takaaki Natsushiro). It debuted in maimai でらっくす FESTiVAL on December 16, 2022, as the centerpiece track of the Sky Street Area 3 (スカイストリートちほー3) story chapter, and later crossed over into SEGA's ONGEKI bright MEMORY. The lyrics grapple with existential weight and the paradox of trying to be kind in a world that feels like a zero-sum game, the opening line, "この世はずっと椅子取りゲームなんだ" ("This world has always been a game of musical chairs"), sets an introspective tone that the subdued 122 BPM arrangement reinforces. The song's title itself plays on "riff" (a repeated musical phrase) and "refrain" (リフレイン), mirroring the cyclical, self-questioning structure of the lyrics. Within maimai's narrative mode, RIFFRAIN accompanies the Sky Street Area 3 storyline, which follows protagonist アカツキ and his friends ナノハ, モモ, and ソウ as strange distortions begin to unravel their reality following the disappearance of コハク. The accompanying music video was produced by 桜井貴志, kairi, Yazhirushi / さくしゃ2, and らにとに～.