Flight Haneda Airport departs from Tokyo Haneda Airport at 11:05 and arrives at Singapore Changi Airport at 17:15.
The flighttime is about 7h 10m. The distance travelled ("as the bird flies"): 4314 Km. So the average speed is roughly 602 Km.
There is an 1 hour time difference between Tokyo and Singapore
The best day to arrive at Tokyo is Tuesday and it would be best to avoid Friday, as prices are on average 115.95% higher than on Tuesday. (Average prices, based on 409181 datapoints.)
We have a lot more statistics for flights GA 841 and between Tokyo and Singapore.