This is a factory, famous in Japan for sauce for yakiniku called Nihon Shokken. The building is based on the Belvedere Palace in Vienna

You can get a tour, but needs to be organised well in advance. Apparently you also get to see the highly automated factory in addition to the museum, garden and take home a number of their goods.

https://en.japantravel.com/ehime/nihon-shokken-s-factory-in-imabari/3755

As we were just driving by we made a brief stop for a couple of photos.