I booked tickets for my friend and I to visit the Ghibli museum in August when we stayed in Tokyo.
The museum is absolutely amazing, I think even if you hadn't seen one ghibli film in your entire life you would still thoroughly enjoy the experience.
However...I was somewhat annoyed that you literally aren't allowed to take any photos at all. I tried to take a sneaky pic on my phone and we ended up being followed by some weird little photo nazi for the rest of the visit. I only wanted a photo of the huge catbus and when I got home I found pictures of it on the Internet already so I have no idea why the ghibli photography police seem to have gone to Charlie and the Chocolate factory extremes to keep their non-secret such a secret.
Lack of photos aside it was a great experience, and one that I will take with me for a long time. For me it had the same magic as Disneyland, but with less rides (no rides at all)
Also if you're staying in Tokyo be prepared for quite a long journey. It's quite far out and in a very suburban area.
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