The Cassiopeia sleeper train between Ueno and Sapporo was discontinued a while ago and we didn't get around to use it while it was still running.
However, the Wikipedia site linked to a feature that mentioned could re-open as a cruise train. I also saw a NHK feature once that showed that it running as a packaged tour by a private operator (albeit only as far as Aomori).
Question: Does anyone know whether this train is still used for tours, and if so how one would go about to make a booking? I didn't find anything online, at least not in English language.