I was skeptical about the wording “pre-order request”. I guess it’s just a request. If Viator is not able to get the tickets for the requested date and time, they would have to cancel the order and refund the money. I don’t understand why Japan is making it so difficult for foreign tourists: the Ghibli Museum, the Michelin Starred restaurants and even Tokyo Disney Hotel/Dining. I have never planned a trip with such stress level such as booking Tokyo Disney hotels, onsen ryokans, Pokemon Cafe, etc. etc. And I have been to a few countries in Europe and US, China, Korea and Hong Kong. I can feel your pain and I am glad that you are able to find something that works for you.