Secret Course 04
From the Super Mario Wiki
The entire course consists of a single room with an arrangement of eight soft platforms. There is also four sets of Hidden Coins around the room along with a single door and Ninji. One Bonus Medal can be found in the middle of the room above a soft platform. Another Bonus Medal is found after revealing one of the outlines at the top left soft platform. The remaining three Bonus Medals are found at the top of the room and can be obtained by jumping off the Ninji. The course ends once the player enters the door.