Consulates with neat architecture
I was in Japan to get my Korean work visa. As a result, I had the opportunity to visit the Korean consulate in Fukuoka. There's nothing really special to see inside, but the outside had some neat architecture. There's a large courtyard, and you can easily take pictures from the street around the consulate. I didn't get a chance to see it, but the Chinese consulate was about a block away. You could probably visit both in under an hour.
To find the consulates, just head towards the Fukuoka Dome. The Korean consulate is right next door to Hawks Town, and the Chinese consulate is one block over.