Monitoring (song)

"Monitoring" (モニタリング, Monitaringu) is a song by Vocaloid producer Deco*27 featuring Hatsune Miku on vocals. It was released on November 23, 2024, and was later included in the album Transform. The song is a Bass house-influenced track with inspiration from Shōwa era J-pop, produced in collaboration with Hayato Yamamoto. Lyrically, the song covers dark subject matter, portraying Miku as an obsessive stalker who stares through the peephole on the door of her victim's apartment. It was extremely successful, spawning numerous derivative works and charting at number one on Billboard Japan's 2025 Vocaloid year-end list. On September 5, 2025, a self-remix, "Monitoring (Best Friend Remix)" was released, with a lighter dance-pop sound. The remix debuted at number one on the Niconico Vocaloid Top 20 chart.