This is a once in a lifetime place to stay - I can't recommend it highly enough. My husband and I traveled to Japan for three weeks and this was a highlight of the trip. It is still cold in the mountains in April, so we bundled up for two nights in the birthplace of esoteric Buddhism and the magic and honor of staying in a temple. The temple was easy to find with Zenbo's instructions, and the train ride to Koya-san was a beautiful ride itself! The room is one of a kind - there are no other rooms like this at the temple - it is very large, and there is a separate sitting room. The entry/guest area is full of brochures of the area. The monks are very open to talking about what the monk life is like, and answered lots of questions about the morning prayer ceremony - we went both mornings! The prayer room ceiling is covered with gold lanterns - a sight to behold!! The temple is very old and traditional - open air - so we had heaters in the room but the rest of the temple is very open to nature. We got to watch the head monk tend his garden and koi pond just outside the bedroom window, we felt like we were behind the scenes!
The food - it was absolutely incredible! Very filling, so many courses, and the most beautiful presentation you have ever seen. They even sell their own sake for dinner!
There are separate, large public baths for men and women, and low showers to sit and wash beforehand, but all toilets are shared. The baths add to the relaxation of the temple.
If you go, be sure to walk Okunoin cemetery in the late afternoon when the lanterns turn on - a stunning visual and spiritual experience. Enjoy Sanboin!