Flight Haneda Airport departs from Tokyo Haneda Airport at 18:20 and arrives at Taipei Taipei Songshan Airport at 20:50.
The flighttime is about 11h 30m. The distance travelled ("as the bird flies"): 2157 Km. So the average speed is roughly 188 Km.
There is an 9 hour time difference between Tokyo and Taipei
The best day to arrive at Tokyo is Friday and it would be best to avoid Monday, as prices are on average 53.94% higher than on Friday. (Average prices, based on 9737671 datapoints.)
We have a lot more statistics for flights JL 99 and between Tokyo and Taipei.