1st time to Japan with 2 boys

Well, I don't know what robot show you're talking about. Maybe the robot restaurant in Shinjuku? And probably the toys building your talking about is the Hakuhinkan Toy store in Ginza. You can look both up on Google. 

Maybe you can tour Tokyo for 2 or 3 days, and then go see Kamakura, and also Nikko if you want to take the bullet train. There's a list of must see sightseeing spots here. http://www.japan-guide.com/e/e2164.html