Regressor Instruction Manual (회귀자 사용설명서) is a Korean fantasy franchise created by the author Heuksuyeo (흙수저).The story was later adapted into a popular webtoon (manhwa) format featuring art by MIDNIGHT STUDIO. The series is best known for its subversion of traditional dungeon-fantasy tropes, focusing on a protagonist who survives through political intrigue and psychological manipulation rather than brute strength.