Flight Changi Airport departs from Singapore Changi Airport at 23:55 and arrives at Tokyo Narita International Airport at 08:00.
The flighttime is about 7h 05m. The distance travelled ("as the bird flies"): 4385 Km. So the average speed is roughly 619 Km.
There is an 1 hour time difference between Singapore and Tokyo
The best day to arrive at Singapore is Monday and it would be best to avoid Friday, as prices are on average 79.03% higher than on Monday. (Average prices, based on 493861 datapoints.)
This graph shows the distribution of prices found in the past years for this flight. (Average prices, based on 133 datapoints.)
We have a lot more statistics for flights SQ 638 and between Singapore and Tokyo.