I found this story just now and must share it with all my Tokyo cycling brethren.
Beginning today the Tokyo Metropolitan Police Department will be cracking down on commuter cyclists on the 10th of each month. During regular commuting hours police will be out on the street watching cyclists closely for traffic rule violations. The police will be stopping cyclists to check their registration, checking that fixies have brakes, ensuring we have headlights etc. and to hand out bicycle safety brochures.
Interestingly, in the event that the 10th falls on a weekend police will be out in force on the Friday beforehand.
So fellow commuters, I know we all bend the rules occasionally, but be careful on the 10th of each month because they're out to get us!
You can read the article in Japanese here.