Driving from Narita Airport to Yudanaka

We are travelin with two young children to Shibu Onsen in February. We plan to rent a car with winter tyres, GPS and drive from narita airport to Shibu Onsen. How long will it take and is it safe? Would greatly appreciate comments.

No safe take a trains.
http://www.hyperdia.com/en/

http://www.shibuonsen.net/english/access.html

Why do you say it is not safe? We are not planning to drive to the mountainous area. Please elaborate. Thank you.

Shibu Onsen is borderline mountainous, and the roads will be snowy, but they should be safe to drive especially if you are experienced driving in snow.

If you are only going to the Yamanouchi area then trains will probably be easier but more expensive. It's a toss up, but I'd probably drive. It takes about 4-4.5 hours without traffic.

https://www.google.com/maps/dir/%E6%B8%8B%E6%B8%A9%E6%B3%89,+Japan,+%E...

Thank you very much for your response.