Flight International Airport departs from Osaka International Airport at 17:00 and arrives at Tokyo Narita International Airport at 18:20.
The flighttime is about 1h 20m. The distance travelled ("as the bird flies"): 556 Km. So the average speed is roughly 417 Km.
The best day to arrive at Osaka is Sunday and it would be best to avoid Friday, as prices are on average 89.08% higher than on Sunday. (Average prices, based on 409690 datapoints.)
We have a lot more statistics for flights JL 128 and between Osaka and Tokyo.