Flight Haneda Airport departs from Tokyo Haneda Airport at 11:25 and arrives at Singapore Changi Airport at 17:35.
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 Sunday and it would be best to avoid Tuesday, as prices are on average 403.71% higher than on Sunday. (Average prices, based on 406818 datapoints.)
We have a lot more statistics for flights JL 37 and between Tokyo and Singapore.