Hi. It will depend on where you are situated. Nevertheless, the cheapest and most convenient mode of transport is by catching a train via JR Oga at Akita Station which will take you to Hadachi or Oga. Then from Hadachi or Oga, grab a taxi to Namahage Museum. Via train will take you at least an hour or so to get there. You may also opt to get there via a shuttle operated by Akita Airportliner from the Akita Station which will take you directly to Namahage Museum.