Please be aware that Bangkok and Tokyo has multiple airports and that these results are for all airports serving the city.
The best month to fly between Bangkok and Tokyo is November and the most expensive month to fly is April. (Average prices, based on 744 datapoints.)
The best day to arrive at Bangkok is Saturday and it would be best to avoid Monday, as prices are on average 74.67% higher than on Saturday. (Average prices, based on 652 datapoints.)
The cheapest airline flying from Bangkok to Tokyo is Thai Airasia X . They are 77% cheaper than All Nippon Airways. (Average prices, based on 752 datapoints.)
The best time to fly is at around 2. (Average prices, based on 1209 datapoints.)