From Tokyo or Ueno Station you catch "Hokuriku Shinkansen" (Bullet Train) to Iiyama Station. It takes about 1 hour and 45 minutes.
2. NOZAWA ONSEN LINER
When you arrive to Iiyama Station you will need to transfer to the Nozawa OnsenLiner Bus which takes about 20 minutes to get shinden(新田) bus stop for the destination Villa Katashio. 600 yen (prepaid)