Hachimantai (Goshogake) day trip

What is the easiest option to reach the Hachimantai area, preferably Goshogake, by public transport?
I tried looking for bus information to Goshogake but this is always such a hassle for me :(
I'd like doing a day trip to the area.

Daytrip from where?

Access to Goshogake is explained here:
http://www.japan-guide.com/e/e3654.html

I recommend a rental car.

Goshogake is impressive.

http://ponkanchan.blogspot.jp/2015/08/logistics-of-hachimantai.html

I have a picture of the timetable for Goshogake here. The services are infrequent and a car would surely be easier. But you do see people using the buses. The page has a link to the English website for buses (more up to date than the photo). Nights are already cool there, so be sure to take warm clothes if you are going.

Thanks for the page, I found it too (or the japanese version).
Somewhere I read this bus is not operated at the moment. But I can't find that page anymore. Maybe it was updated.
Still, it would leave me just 4 hours to hike as the last bus heads back to Tazawaka at 15:04 (I hope I read the shedule right).
I guess that is not enough time and too much of a hurry.
Unfortunately I can't rent a car.

Consider contacting Senboku City's tourist information.
One reason is that they should have good and up to date information.
The second reason is that it puts the fact there is a demand for transport in the area on their radar. If they get inquiries and see a demand, transportation may improve...
A good start would be translating the website of the Akita Nairiku line (though that doesn't help with getting to Goshogake).

I will see if I can formulate an email to them :)

Goshogake is in Kazuno city rather than Senboku, but the tourist infrastructure seems much better in Senboku (Lake Tazawa, Kakunodate, Shinkansen line). It's possible that they're a little territorial, but they should still be helpful.

They should have English speakers on staff.