FestivaLight is the opening theme song of maimai MiLK PLUS, the second major content update to SEGA's maimai MiLK arcade series. Composed, written, and performed by veteran Japanese singer-songwriter Haruka Shimotsuki (霜月はるか), the track was released on June 21, 2018, as the flagship tune for the update. The game's promotional material playfully framed MiLK PLUS as the "second season" of a fictional anime, with FestivaLight as its opening theme. The title is a portmanteau of "festival" and "light," and the lyrics depict a quiet town coming alive on a special celebration day, neighbors dressing up, streets adorned with colorful ribbons and flowers, the scent of fresh bread and tea in the air, and music drawing everyone into the square to dance hand-in-hand. At a warm 125 BPM, the song carries an upbeat but gentle pop energy that mirrors its message of communal joy. The accompanying music video, produced by MiRA, features the maimai original mascot characters, Ras, Chiffon, Salt, and Otohime, enjoying a festival setting, with silhouettes of the duo Shama & Milk visible in the background. Within maimai itself, FestivaLight was later placed in the 10th Anniversary Area (10周年記念ちほー) as a quest song, sequenced between Believe the Rainbow and Magical Flavor. Outside of maimai, the song appears on Haruka Shimotsuki's album "Otonoha letter ~Ame no Oto~" (おとのはレター ～Ame no Oto～), and it later crossed over into SEGA's companion rhythm game ONGEKI as part of the bright MEMORY update on September 15, 2022. On the chart side, FestivaLight's MASTER chart, designed by ぴちネコ, stands out for its unusually high Slide-note count (91 out of 592), giving it a sweeping, flowing quality that mirrors the song's festival-dance character.