I don't know that Tokyo is particularly unique, cycling-wise. Bikes are considered light vehicles and are supposed to travel on the road, with the traffic. That doesn't stop the majority of housewives and students on shopping bikes from riding on the sidewalks and terrorizing pedestrians, or from riding on the road against the traffic and terrorizing drivers and serious cyclists. Tandems are illegal. Otherwise, I don’t think Tokyo is either more or less cycle-friendly than other major cities.
There is an active roadie scene, but the Japanese police are generally unwilling to give permission for open-road races. Aside from the occasional century ride, amateur racing is pretty much limited to closed-circuit crits and hill-climbs. The hill-climb races are the highlight for me, and the largest of the year attracts 4,000 riders for a 1,400 meter 24 km climb.