Make sure that you do not collect the red coin in the first room, as well as the red coin in the last room in the black box. Get the other six coins. Then, use Wario to break the black box and collect the seventh red coin, then fall into the hole. You will appear in the first room. Collect the eighth red coin. You will hear a chime that reveals the star, but not see the star. Go to the last room without falling, dying, or choosing the wrong door. You will see two stars, Note: If you never collected the star before, it will make two yellow stars, but when you will pick up the other star it will not count in your star total.