We are spending a night at a temple in Koyasan. We plan to travel from Kyoto, stay a night then travel the next day ( a Sunday) back to Tokyo. I have tried to look the trip up on hyperdia and it says 'route not found'. Any suggestions?
JR does not go to Koyasan, so you need to take a different train line (Nankai). The problem you are likely having is the train line to Koyasan is currently down due to typhoon damage, so substitute buses are running for that section. If you are not aware of the the Koyasan World Heritage Ticket https://www.japan-guide.com/e/e2358_012.html It's a good money saver.
At any rate, the main rail connection would be at Hashimoto Stn. Here would be the route: http://bit.ly/2pf1Cso Just change the date and time to when you are traveling and rerun it. More important info is here: https://www.japan-guide.com/e/e4904.html
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If you are not aware of the the Koyasan World Heritage Ticket
https://www.japan-guide.com/e/e2358_012.html
It's a good money saver.
At any rate, the main rail connection would be at Hashimoto Stn. Here would be the route:
http://bit.ly/2pf1Cso
Just change the date and time to when you are traveling and rerun it.
More important info is here:
https://www.japan-guide.com/e/e4904.html
Here's some more information on the substitute bus that's currently running from Hashimoto to Koyasan:
http://www.nankaikoya.jp/en/images/pdf/for_passengers_201801.pdf
Hope that helps.
Japan Experience