This temple, located in Tochigi, is really beautiful. It has to be on of my favorite places in Japan so far. The setting is just magnificent. And its frequently pretty quiet too so you can really relax and enjoy the place.
I'd think you would need a car to get to this temple. You could probably bike from Otawara but it would be at least 20 km each way I think.
Its a fairly short visit. Its a small place. It will probably just take half an hour to get around it. Fortunately its right near -Daiyuuji, link to blog article, write it first!- which has some great gardens and a museum so you can probably make a trip out of that.