Navigation help to Okama crator

I am planning to visit Okama crator this Sunday. I am coming from Tokyo and need to go back in the evening.
I plan to come from Tokyo to Yamagata by Shinkansen and from Yamagata, take a car and drive to Kattadake peak.
Hope this is the good plan and let me know if you have any other suggestions.

Also i want to know the telephone number in Kattatake peak for better car navigation. I cannot understand Japanese; so usually use telephone nu. navigation.

The drive to Okama is just under an hour from Yamagata Station.
https://goo.gl/maps/Hd7RhFEKoMU2

Note that part of Rte 12 known as the Zao Echo Line and Zao Highline (toll required) is closed during winter time and normally the period starts from early Nov. Monitor the situation and make sure it is still accessible this coming weekend.
http://www.zao-machi.com/546

For the GPS it is more accurate to enter the mapcode of the destination. Mapcode of the Kattadake car park at the road end of the Zao Highline is 569 429 811. There is a 540 yen parking fee.

Unfortunately already "Witer (Road) close" starts.
fr yesterday 4 Nov 17:00 to Next 2017 late APR.
http://www.zao-machi.com/category/information
"28" and "29" means Heisei period in Jp.
https://en.wikipedia.org/wiki/Heisei_period

Especially this week Thu - Fri(3 Nov) falling snow a lot.
http://www.kahoku.co.jp/tohokunews/201611/20161103_13012.html

So that plan should be cancel.