When you were a kid and you have tried to wear a t-shirt on your face to look like a Ninja, then you definitely need to visit Edo Wonderland in Nikko. This place draws out your childishness just like when you visit Disneyland for the first time.
Edo Wonderland is a theme park that was made to look like it was a village during the Edo era. This also means that all of the theme park staff are dressed old school (samurais, ninjas, geishas, etc..). As an added treat, they provide costumes as well so you can literally feel and enjoy the atmosphere of Edo Wonderland.