マツヨイナイトバグ (Matsuyoi Nightbug) is a Touhou Project arrange produced by the doujin circle COOL&CREATE, featuring vocalists beatMARIO (ビートまりお) and MARON (まろん). The track was originally created for the mobile rhythm game 東方ダンマクカグラ (Touhou Danmaku Kagura) before arriving in maimai DX UNiVERSE on November 12, 2021 as a cross-title collaboration piece. It later spread to CHUNITHM LUMINOUS PLUS and オンゲキ Re:Fresh, making it one of several Touhou tracks shared across Sega's rhythm game lineup. The song arranges 蠢々秋月 ～ Mooned Insect, the stage 1 boss theme from 東方永夜抄 ～ Imperishable Night (Touhou 8) composed by ZUN. The arrangement and lyrics were handled by beatMARIO and MARON, with additional vocals from Amane and guitar work by Tera. The title itself is a layered pun: 待宵 (matsuyoi, "the evening of the 14th" or "waiting for night") combines with "night bug" to echo both the insect motif of the original theme and the song's central metaphor of a world full of "bugs" (glitches/bugs). The music video, created by 夜好ころろ (Encore+), was eventually adopted as the in-game background movie starting with maimai DX PRiSM, replacing an earlier gameplay capture from Touhou Danmaku Kagura. Lyrically, the song is playful and frenetic, the chorus shouts "バグれ！バグれ！" ("Bug out! Bug out!") and weaves imagery of danmaku, fireflies, and the eternal night of Touhou 8's story. References to "LUNATIC" difficulty and the phrase "Imperishable Night" directly anchor the song to its source game. On the charting side, the song received five DX charts across three designers: はっぴー (Happy) on Expert, 翠楼屋 (Suirouya) on Master, and ぴちネコ (Pichineko) on the Re:Master chart added in PRiSM (October 2024). The Re:Master chart at level 14 is the densest of the set, with 1,127 total notes and a notably high count of Touch (132) and Break (164) notes that give it a distinct tactile feel compared to the Master chart.