Alex,
I attemted this last month while on a mileage run to TPE.
I would recomend against going to Toyko,for the fact that you will have less than 12 hours,in town.
cost of train to city 60.00 to 100.00 US also high cost of rooms in toyko.
after clearing customs and waiting for the train at best you will arrive at 730 pm.
I also think you might need more time in the morning to NRT.