雑魚 (Zako) is a Vocaloid original song by producer 柊マグネタイト (Hiiragi Magnetite), featuring 亞北ネル (Aone Nera), a derivative character built on the Hatsune Miku voicebank, with 重音テト (Kasane Teto) contributing chorus vocals. It entered the maimai DX arcade rhythm game on April 3, 2026 as part of the CiRCLE PLUS version update, marking the first time a 亞北ネル vocal track has appeared in the series. The song carries an unusual publication history. It was originally uploaded to niconico under the title ざぁこ (Zaako) sung by 歌愛ユキ (Kaai Yuki), but was taken down within less than a day amid circumstances that attracted significant online discussion. A remake followed shortly after with the revised title 雑魚, replacing the lead vocal with 亞北ネル (derived from the Hatsune Miku database) and adding Kasane Teto on backing chorus. Both title variants, 雑魚 (zako) and ざぁこ (zaako), are Japanese pejorative slang meaning "small fry" or "loser," a theme that extends into the game's deluxe collection rewards: players who trigger a track skip earn the title "くそざこ" (complete trash), while those who lose in a multiplayer session earn "ざぁこ." In maimai, the Master chart sits at level 13.1 and was designed by Luxizhel, known for dense Slide-heavy arrangements. The Expert chart (level 10) was handled by サファ太 (Safata). The song is currently available only on Japanese-region cabinets.