My travel plan in Japan.

Hi, I'm going to visit Japan from 8th of May to 10th May with my family.
Purpose of this trip is to rest at comfortable ryokan.

First day, I'm going to rent a car from Narita airport and to visit Nikko. After traveling Nikko for about 3 hours, I'm going to drive to Karuizawa.
I know there are plenty of things to see in Nikko, but I don't have much time. I'm supposed to arrive in Narita at around 11 o'clock. So I just want to see the most famous spot in the Nikko. I think 3 hours would be enough for that.

I'd like to ask that the time from Nikko to Karuizawa city. And please check my travel plan that it is feasible.

Thank you for your time.

If you arrive in Narita at 11:00, you can expect to start driving at noon, at the earliest. Possibly later. The drive from Narita to Nikko takes about three hours, if you can find your way through the expressway jungle of Tokyo. It could take considerably longer if you end up on a wrong lane, miss your junction and get lost.

So, if you encounter no major problem, you should arrive in Nikko around 3pm. The temples and shrines of Nikko close around 5pm. That does not even leave you three hours of sightseeing.

Driving from Nikko to Karuizawa can be very pleasant along the "Romantic Road", but it takes at least four hours:
http://www.japan-guide.com/e/e7450.html

If you take a faster route via expressways, it might be possible in about three hours.

Obviously, Narita - Nikko - Karuizawa is not feasible within your first day. But if you overnight in Nikko, it can be done.

I also recommend to consider taking a train or bus from Narita to Nikko or nearby Utsunomiya and rent a car from there to avoid the challenging drive through Tokyo.

I know Karuizawa is a well-known highland resort, but there are also famous highland onsen resorts near Nikko.

So if you can still change your place to stay, I'd advise you to find a ryokan in Kinugawa, Nasu or Shiobara to shorten your travel time from Nikko.

Kinugawa
http://www.jnto.go.jp/eng/location/regional/tochigi/kin...

Nasu & Shiobara
http://www.jnto.go.jp/eng/location/regional/tochigi/nas...

From Nikko to
Karuizawa : 4 hours
Kinugawa : 1 hour
Shiobara : 1 1/4 hours
Nasu : 1 1/2 hours

from these area, you can also visit Nikko on the 2nd day or 3rd day.

The Imperial family of Japan own their resort villa in Nasu and usually spend their summer vacation there. I think these areas are as fascinating as Karuizawa. Just FYI.