'Yin Yang Road Eight: The Coffin Boy') is a 2000 Hong Kong comedy horror film produced by Nam Yin and directed by Edmond Yuen.
While moving in, Bud Pit accidentally knocks over a small incense stick holder and is disturbed by a spirit for a while.
While he is initially attracted to his new cheerful neighbor Olive, he becomes suspicious of her when he sees her roaming the streets at night, not recognizing him and behaving like a completely different person.
He tells his mother, the expert ghostbuster Mrs Bud Lung, and she unravels the mystery.
Mrs Bud Lung promises to help the ghost reunite with her (also deceased) son on the condition that she leaves Olive's body after the reunion.