Mt Aso and Horseback Riding

I keep reading about horseback riding at Mt Aso, but can't seem to find much information about actually booking it. One place on groupon Japan is having a sale, I think its called "Aso Highland Riding Club Otohimehiˆ’‘hƒnƒCƒ‰ƒ“ƒhζ”nƒNƒ‰ƒu@ƒGƒ‹EƒpƒeƒBƒI‰³•Pjbut i can't seem to find any info about it in English. Here is the groupon link

http://www.groupon.jp/cid/26918

Also, if anyone knows other places they've used and liked that would be helpful!

You can do some simple horse riding without prior reservation on the Kusasenri-ga-hama plain near the summit of Mount Aso (except December to February):
http://www.japan-guide.com/e/e4552.html

The cost per person:
5 minutes: 1300 yen
20 minutes: 3000 yen
25 minutes: 4000 yen

From: http://www.asocity-kanko.jp/spots/view/5

In addition to the one in Kusasenri there are 2 hoseback riding ranches in the area of Aso with web information, but only in Japanese.
http://www.gv-aso.com/gv-hp/
http://epr-r.com/index.html

There is even a short video on the El Patio Ranch in the following:
http://www.webtv-aso.net/video_player/ss090811001.html