Not a bad rate at all. While I can't say with any certainty that this is an error rate, the fact that it does not show up on the initial search results page (where supposedly each property presents their cheapest rate for the search parameters inputted), does give some weight to this possibility.

Sapporo hotel rates are, on average, much less expensive. The Sapporo Sheraton, for instance, is going for 7700 JPY on the same date. (And Sapporo is really quite nice this time of year.)