Flight Narita International Airport departs from Tokyo Narita International Airport at 18:00 and arrives at Jakarta Soekarno–Hatta International Airport at 23:55.
The flighttime is about 7h 55m. The distance travelled ("as the bird flies"): 4356 Km. So the average speed is roughly 550 Km.
There is an 2 hour time difference between Tokyo and Jakarta