I also do think that your schedule is packed with a lot of activities. Is this your first time in Japan?

Have you considered possibility of jet lag? It is pretty much day and night reversed between Chicago and Tokyo. It is not unusual to start feel tired and sleepy during afternoon. There is possibility that you or your son will start feel tired and sleepy after lunch. It is possible that first a night or two you or your son may not be 100% to go out for dinner after that long day packed with activities. I think your schedule is pretty packed even without considering jet lag.

I also agree with DaveNCL that your 8 year old son may quickly find items on your schedule to be bit boring after a day or so. But you know your son better than any of us.

How about food? How does your 8 year old son handle Japanese food? Food in Japan can be different than Japanese restaurants in Chicago area.