Flight Haneda Airport departs from Tokyo Haneda Airport at 09:15 and arrives at Singapore Changi Airport at 15:15.
The flighttime is about 7h 00m. The distance travelled ("as the bird flies"): 4314 Km. So the average speed is roughly 616 Km.
There is an 1 hour time difference between Tokyo and Singapore
The best day to arrive at Tokyo is Monday and it would be best to avoid Thursday, as prices are on average 94.19% higher than on Monday. (Average prices, based on 402460 datapoints.)
We have a lot more statistics for flights SQ 631 and between Tokyo and Singapore.