When you go to the hot springs in Japan, you're naked, save for a small towel if you so desire. Well, not like on the train ride there, but you know what I mean.
So in Wii title Muramasa: The Demon Blade, the characters are just that — naked in a hot spring, save for a small towel.
In the game, the hot springs, called "onsen" in Japanese, recharge your character and sword energy. You can also run into other characters or even boars while in the hot springs.