CheapFlights.gr will find you the cheapest flights from Tokyo to Hanoi, comparing the cost of the flight to Hanoi with 45 agencies, 5 booking systems and 718 airlines. Where to buy Tokyo - Hanoi plane tickets - it's up to you.
It should be noted that depending on the number of days left before departure, the price of a ticket for a Tokyo - Hanoi plane can change by more than 59%.
CheapFlights.gr suggests buying air tickets Tokyo - Hanoi in advance, then you can choose the conditions of the flight, focusing on your wishes and financial opportunities.