In order to get advanced treatment, you need to earn a lot of coins. The arena where you fight is called an instance dungeon, and you can earn a large amount of coins at once. If you die before you get any coins, you can go there. But if you die in the instance dungeon before you earn a single coin, you're welcome to the ghost prison. You'll get more coins for treating your disease if you clear the dungeon. The ghost prison looks like a prison, but it's actually a battle arena. There are only one person in the arena at a time, and the winner of each square will advance to the next.