Happy Ghost II (1985) on Netflix

Plot summary

The ghost of Scholar Stewart Pik is reborn as Hong Sam Kwai, a high school teacher. He is the first man to take on a class that has worn out more women teachers than anyone thought possible, and his students greet him with endless pranks. Kwai has natural powers he does not yet know how to use, and Uncle Tang, who works in the school canteen, shows him how to avoid the tricks the class plans. When his job is on the line, Kwai must find a way to reach his students and restore his name. Boys from a nearby school fall for his students, and Kwai falls for Miss Lo, who works at the boys' school.