Detective Conan (1996)

High school student Shinichi Kudou has always been known for his great detective skills which enables him to solve whatever challenging or difficult cases there are. One day, Shinichi follows two suspicious men and became a witness to an illegal activity. However, they caught him watching and dosed him with a drug forumlated by their own organization, leaving him to his death. But to his surprise, Shinichi still managed to live - except he's now in the body of a seven-year-old.