Excellent place to trek. Highly recommended. It took 2 hours to come from Tokyo by train and 1 hour to climb but the sights and masonry work around the temple grounds made for time well spent. Be aware, take water with you and limited stuff to carry. We took cable car on the way down.
I visited Nihon-ji Temple on February 5 last year. The atmosphere was beautiful and worth the trip. The walk from Karamura Station was a bit long, but there were restaurants and souvenir shops along the way. The temple was crowded but easy to explore. Don’t forget to visit the souvenir shop in front of the temple—the snacks are delicious!
700円 entrance for the temple. Nice views. Free parking on premises. You’ll need to climb some steps to reach the entrance and then again to the statue.
There are a couple options to get to this location. First being the Nihon-ji temple parking which is free and closest. Second is the Nokogiriyama parking, which farther away, short walk to the Daibutsu, but the return can be a trek. Last is the Nokogiriyama ropeway, lots of stairs. Great workout and great atmosphere. The air quality here is wonderful!
The Buddha is very impressive. It is definitely worth a visit. Depending what you would like to see and whether you want to challenge and walk up and down thousands of steps (literally), there are options. If you are only interested in seeing the giant Buddha and the temples, then my suggestion is to drive to the east entrance car where the Buddha is not too many steps away, then if you follow the path to the left, you can see the various temples too and with minimal steps.
This does mean you are not going to walk up and down all the steps and miss out on the statues dotted around the mountain, the view of hell from the top and the ropeway. The ropeway you can do separately by just going up and then down again without re-entering the temple.