Makouseinen B.T.: "Busou Smoker" Jiken

The spin-off stars an adult B.T., who is employed at Dinosaur Hotel in Las Vegas as a magician. After watching B.T.'s magic show, Koichi Mugikari learns that B.T. is actually employed for helping the hotel's casino handle gamblers who have unusual winning streaks.

(Source: JoJo Wiki)