Ride

You can take a look at this page: "Orientation in Tochigi" or "access in Tochigi" https://planetyze.com/en/japan/tochigi/orientation 
it says:

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Transportation

Taking the train from Tokyo is the usual way to go with the Tokaido Shinkansen (Bullet Train) reaching Utsunomiya in about 50 minutes while conventional trains take about 2 hours. There are 2 ways to head for Nikko: there is JR from Tokyo via Utsunomiya or taking the Tobu Line from Asakusa Station. It is also possible to travel by car from Tokyo over the 180km to Nikko. And since there are plenty of trains and buses serving the Nikko area, you will want to use them effectively because there will be busy times during events such as the fall colors.
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The ride will cost around  ¥3300 - ¥4700 yen.

Here is a map you can use.

I recommend hiring a guide in Tochigi because it will be hard to make the most out of your time without one.
You can see tours in Tochigi here: https://planetyze.com/en/japan/tochigi/bookings/tours
You can see guides in Tochigi here:  https://triplelights.com/japan/tochigi/guides 

I hope this helps!