Staying in the temple for two nights was the most amazing part of our two great weeks in Japan. We travelled with three adults and two kids (13 and 9 years). We had a very large double room, which was mesmerizingly beautiful in its simple japanese design. Air-condition was lovely during the hot summer season, worth mentioning when traveling with kids: the doors of the room etc. are literally from paper.
We felt very welcome, also the kids. Communication in english was easy. The public bath was a pleasant experience, toilets were shared with other guests, clean and close by.
Being able to participate the morning ceremony was an honour, and and impressing experience for the whole family.
We went for a maybe 8km walk, north from the village uphill, on a forest street, entering the famous Koyasan cemetery from uphill, and it was super nice!
Small important detail: when entering sacred areas, also the cemetary, you are expected to cover your shoulders, and of possible also your legs with appropriate clothing.
If or when visiting Japan again we will be happy to visit Koyasan again.