The amount actually charged to my credit card was about 1,500 yen higher than the amount displayed at the time of payment.
When I inquired about it, a new price was displayed and I agreed to it, right? I received a similar message and was told that it was not possible to refund the difference or cancel the order.
From the beginning, I researched the product's reputation on the internet and knew to be wary of people who can't speak English, so I took a screenshot of the product at the time of purchase to leave proof.
There was no new price displayed, and there was a screenshot from when I purchased it, so even if I said I had proof, they wouldn't take it.
I searched on Travelco and found it was the cheapest, so I tried using it, but in the end I think Trip.com was cheaper.
I'm going to give up this time, thinking it's just a learning experience.