Upvote:5
TL; DR: I suspect that the Tokyo Olympics would not make a significant difference.
I have been in Beijing during the 2008 Olympics, which were much more high-profile. The Chinese government took it much more seriously than the Japanese government does.
In general, very little changed. Yes, there were security checks, which were annoying. Yes, there was more traffic congestion, but probably because Beijing has always been a congested city anyway (Tokyo is much, much better in this respect, given most people travel on the railway). We stayed clear of the main Olympic area in Chaoyang district, as that was REALLY congested (there was very little rail transportation in that area in Beijing at the time). It could be occasionally annoying, but most of the time I didn't feel much, because Beijing was already a huge city!
On the flip side, it was great to be in Beijing at that time! The shops and waiters were more friendly (Beijing was known for shop staff with bad attitudes), the city was much cleaner and much more well-managed, and the public transportation was also much better managed. Plus, you get to watch the Olympic Games! Tickets for preliminary events, for instance, are cheap and easy to buy. That would be a great opportunity for your students.
Conclusion: Given that Tokyo is already the world's largest city (by certain definitions, of course), it is not really imaginable that the Olympic Games would have a large impact on things that happen in the city. The Yamanote Line and the subways might be more congested than usual (it would already be quite a scene for most Canadians anyway), and you might see more policemen out there, but I can't think of any real impact. Airfare would likely be influenced significantly, but given that the Olympics are very short (July 24 to August 9), your group could very easily schedule around that.