I can't believe it dates back to the 14th century, it looks pristine! Of course, you have mentioned that it got some restoration help but still! Just wow! And the details are fantastic.
Would be interesting to see the inside of the castle, is it allowed?
Yes you can visit from the inside, I have been in there twice. It is like a little museum with lots of artifacts from the samurai and feudal times. But I prefer to just wander around the castle ground and appreciate the look from the outside.