Can I get additional insurance after making a reservation?

[Common to Japan / Thailand] This is possible only before the itinerary starts and if you have not changed the reservation details. Please make additional subscription procedures from your own reservation confirmation page. If you change the reservation details after purchase You cannot subscribe to the website additionally, so please subscribe by yourself from the following.
https://www.chubbtravelinsurance.jp/zipair

Travel cancellation insurance can only be purchased on the ticket reservation line of Japan origin roundtrip/oneway ticket.