Tourists bound for Koyasan by Nankai railway have to take a substitute bus at Nankai Hashimoto Station as the train service has been suspended between Koya-shita and Koyasan station due to a large-scale landslide occurred at the end of October, 2017. As of January 10, 2018, the terminal bus station of Koyasan was changed from Koyasan station to Daimon Minami Chushajo. From Daimon Minami Chushajo, you can walk 10 minutes to Daimon, the principal entrance to the precincts of Koyasan, or take another free substitute bus up to Kongobuji-mae. To go further to Okuno-in, you need to take another bus for which you need to pay.
For detailed information, please check the notice of Nankai Electric Railway; http://www.howto-osaka.com/global/pdf/notice/180110/furikae_koyasan_en.pdf