In general, when booking your flight to Tokyo, November is the cheapest month on average.
From most locations, booking your flights to Tokyo around 60 days prior to your departure date finds the best deals.
Most of our users find that booking their departure to Tokyo on a Tuesday is the cheapest. Conversely, departing on a Friday seems to be the most expensive.
On average you can find the best deals on plane tickets to Tokyo when looking for flights with afternoon departure times.