ツムギボシ (Tsumugiboshi) is the theme song of maimai でらっくす FESTiVAL PLUS, composed and written by Kanon Oguni (大国奏音) with vocals by timao. It marked Oguni's first commissioned vocal composition for the maimai series, prior to this, he had contributed instrumental tracks such as 封焔の135秒 and collaborated on team compositions within the SEGA sound team. The vocalist timao is also a SEGA-affiliated singer, making this a wholly in-house production. The song and its accompanying flavor text evoke imagery of a starry night sky, shooting stars, and the characters of CAFÉ MiLK making wishes beneath the constellations, fitting the FESTiVAL season theme. Released on March 23, 2023, ツムギボシ debuted as a Perfect Challenge reward in the Happy Fes Area 2 (ハピフェスちほー2), requiring players to accumulate 700 km of total distance to unlock it. It was the first maimai DX-era theme song to be gated behind a Perfect Challenge, a distinction previously held by 夢花火 in the original maimai era nearly six years earlier. The song was also pre-released on the limited FESTiVAL goods campaign album "maimai でらっくす グッズキャンペーンDiSC -FESTiVAL-", marking the first time a maimai version theme song debuted on a goods campaign disc. The MASTER chart, designed by じゃこレモン (Jako Lemon), was originally assigned a level of 14, making it the first theme song to hold that distinction in the DX era. It was later adjusted down to 13+ (constant 13.9) starting with the PRiSM version. The EXPERT chart was designed by Jack. Outside of maimai, ツムギボシ has appeared in GROOVE COASTER WAI WAI PARTY!!!! as part of the maimai DX + ONGEKI collaboration pack, and a vocal cover by ONGEKI characters (starring Tsumugi Shinonome, Koboshi Inohara, and Akari Hoshizaki) was released on the ONGEKI Memorial Soundtrack Nexture 03.