Please be aware that Tokyo has multiple airports and that these results are for all airports serving the city.
The best month to fly between Tokyo and Singapore is May and the most expensive month to fly is March. (Average prices, based on 502 datapoints.)
The cheapest airline flying from Tokyo to Singapore is Singapore Airlines. They are 48% cheaper than Japan Airlines. (Average prices, based on 512 datapoints.)
The best time to fly is at around 8. (Average prices, based on 628 datapoints.)