It is possible to get to Sasama entirely by public transport.  However, the schedules for some of the bus and train lines are infrequent and the bus does not run on Sundays or public holidays.  Therefore, while public transport will be the lowest-cost option it may not suit your itinerary.  Please plan in advance and enjoy the journey! 

Coming from SHIZUOKA (静岡) city (for example, from the bullet train) by private car or taxi:

Take Route 362 northeast to KYUUNOO (久能尾) where you make a left turn onto Route 32 to KIYOSASA TOGE (清笹峠).  At the top of the pass make a right turn onto Route 63 toward KAWANE (川根).  At ISHIGAMI (石上) (one of the villages of Sasama) turn north for 3 km to AWABARA village (粟原).  As you enter the village take the first road bridge across the river and turn right up the hill.  Parking is available just outside the estate grounds. Alternatively, take Route 1 from Shizuoka to Shimada and then Route 64 north up the OOIGAWA valley to the SASAMA turn off onto Route 63.  This will bring you to ISHIGAMI (see above).  This route is longer but on better roads. 

Coming by train or bus via SHIMADA (島田) or KANAYA (島田): 

Alight at SHIZUOKA station if coming from TOKYO, or KAKEGAWA (掛川) station if coming from NAGOYA, KYOTO or OSAKA.  Then take a local TOKAIDO line train to SHIMADA (島田) or KANAYA (金谷) (these stations lie between SHIZUOKA and KAKEGAWA). 

If you are planning to take a taxi, SHIMADA is a better option (~50 min). 

If you wish to continue your journey by train, KANAYA is your stop.  At KANAYA transfer to the OOIGAWA line (just next door to the station where you alight).  Take the OOIGAWA line from KANAYA to IEYAMA (家山 ) station.  Train schedules for this line can be found here:  http://oigawa-railway.co.jp/en/ft_timetable.html . 

From IEYAMA station there are three buses each day (Monday-Saturday) to SASAMA (笹間).  These depart at 7:25 (arriving AWABARA (粟原) at 8:10), 11:50 (arriving AWABARA at 12:35) and 16:12 (arriving AWABARA at 16:57).  (*Returning, these buses depart AWABARA at 8:36, 13:31 and 17:26).  Alight at AWABARA-SHITA, cross the wire suspension bridge and climb the small hill to the estate (approximately 3 min on foot).

Here is the address in Japanese (show to taxi/bus drivers): 静岡県島田市川根町笹間上 (粟原) １３２３