Yunotai Hotsprings Run
湯ノ岱温泉マラソン大会
Running
10k, 5k, 3k, 2k
10:00 Start
3,000 yen for adults
1,000 yen for children
Application period: May 18 to June 17
Where: In the land of gods. Kaminokuni! Near Hakodate and Okushiri. A long way away from where I'm at here in Tokachi.
Event URLs:
http://yunotaionsenmarason.wix.com/yunotai
https://www.facebook.com/yunotai/
It looks like they have used Sportsentry in the past.
See: http://www.sportsentry.ne.jp/event/t/22297
You can download the event PDF from their website.
Since this event is past already, I'll have to keep an eye out for the information for next year's event.