I am glad you and your friends had a great time in the Burgh' Jerry. I am thinking that the hamburger joint is a classic called "white castle" of which the first was in Pittsburgh. It has been around a LONG time, and actually most grocery stores in this area at least have the little mini burgers (frozen) for sale. I do not know if it is nationwide or not. If that was not the location, it may be a little independant place which is right down the street from the hotel, but more then likely it was the White Castle. Sound familiar?
My favorite dish at the Kiku is actually the Tako (octopus). It is a really fresh, firm, white meat which I have acquired a strong preference for over the years. Sometimes I like it better than Lobster!
Let me know if you make it back this way, as I can recommend some really good new places to eat which are new to the area. Enjoy your day!