Noboribetsu Date Jidaimura is unapologetically theatrical: reconstructed Edo-period streets, ninja performances, oiran dances, shops, games, and visitors wandering around in rented costume. It is not a museum in the strict sense, but it is fun if you meet it on its own terms.
It works especially well for families or for a rainy half day when the onsen trails are less inviting. Allow time for the scheduled shows rather than just walking the streets.