予約後(支払い後)にホテル名が明らかになる料金制度

--- The definition is rather long, but this is the meaning of "opaque rate" according to the websites I've visited:

http://www.travelmole.com/stories/1116251.php
The biggest increase for Internet bookings was the almost 9% increase among opaque distribution channels reservation sources that reveal the identity of the booked hotel only after a reservation has been placed.
http://www.xotels.com/en/revenue-management/revenue-manageme...
We hear a lot of talk about Opaque Pricing and Opaque Travel Websites, but what is it really? It is in short a non-transparent value offer. What??? This needs to be explained in a bit more detail, right?

A non-transparent value offer, or pricing opacity, basically means that you can’t see the brand of the product type you are buying. It allows hotels to offer discounts, varying with great range from their public prices, without affecting their price positioning.

Wikipedia defines Opaque Inventory as follows: a term used to describe the market of selling unsold travel inventory at a discounted price (click here for more).

It is called ‘opaque’ because the supplier, in this case the hotel, remains hidden until after the reservations (purchase) is complete.

It allows hotels to reach more prices conscious consumers apart from their direct target markets. This type of hotel guest is less concerned with the specifics of the hotels facilities and services. Instead he is driven mainly by price.