アマノジャクリバース feat. ｙｔｒ is a Touhou Project arrange by the doujin circle 魂音泉 (Tamaonsen), built around Seija Kijin's stage boss theme from 東方輝針城 ～ Double Dealing Character. The arrangement was handled by Coro, with lyrics and vocals by ytr. It originally appeared on Tamaonsen's 2015 compilation album THE SELECTED WORKS OF TAMAONSEN 3 before arriving in maimai with the MiLK PLUS update on October 2, 2018. The title fuses 天邪鬼 (amanajaku), a Japanese folkloric spirit defined by its contrarian, opposite-doing nature, with the English word "reverse," directly reflecting Seija Kijin's ability to invert anything. This inversion theme runs through the song's lyrics and its chart identity: the MASTER chart (level 13+, constant 13.9) was originally credited with the simple note "合作だよ" (it's a collaboration) before being formally attributed to designers はっぴー and Jack. Its 777-note count and dense slide-laden patterns mark it as a signature upper-difficulty chart in the MiLK PLUS era. In earlier cabinet versions (through FiNALE), the song played over an animated background featuring Seija Kijin; this was replaced by a static jacket illustration when maimai transitioned to the でらっくす series. The song later received an UTAGE (宴 / party) chart in the CiRCLE update with a mirror-gimmick attribute, and crossed over into CHUNITHM X-VERSE-X in early 2026.