Being the glutton for punishment I am (as well as being a cheapskate) I have continued to find what I think are suitable hotels then calling the concierge to get it booked.
I found a hotel that had rooms available on booking.com and had their own official booking page that didn't require registration and called the concierge again then they told me the room was not available for my dates and that booking.com buys a bucket of rooms and then resells them.
But yesterday (8/22) I tooled around on their own website and found availability so I called in again. I had to coach the concierge through going to their official page and having to use Google Chrome to translate the Japanese booking page to be able to go through the booking process. It took a while navigating the less than user friendly page that's also being translated via Google to finally make the booking. Supposedly. And he confirmed that I'll get the 4th night credit once the booking is paid for.
So I'm supposed to get a confirmation email within 24 hours (it's been about 18 hours so far), until I get that email, I don't think I can actually assume it'll happen. Let's see what happens.
Overall, it's taken about 6-7 separate phone calls each lasting about 20-30 minutes and my time looking up suitable hotels. I'd be saving US$165 on a US$740 booking. I guess it's still worth it... barely.