Flight Narita International Airport departs from Tokyo Narita International Airport at 09:35 and arrives at Shanghai Pudong International Airport at 12:20.
The flighttime is about 3h 45m. The distance travelled ("as the bird flies"): 2092 Km. So the average speed is roughly 558 Km.
There is an 1 hour time difference between Tokyo and Shanghai
The best day to arrive at Tokyo is Thursday and it would be best to avoid Wednesday, as prices are on average 690.3% higher than on Thursday. (Average prices, based on 195590 datapoints.)
We have a lot more statistics for flights JL 873 and between Tokyo and Shanghai.