Akiha Main Shrine 秋葉山本宮秋葉神社
Head shrine of the Akiha shrines since 1952: the walk up from the bottom takes an hour and a half to two hours.
The shrine changed its name several times over the centuries (from 岐陛保神ノ社 to 秋葉大権現, then 秋葉神社) until it became ‘秋葉山本宮秋葉神社’ in 1952, when it received the title of head shrine of all the Akiha shrines in Japan (the literal statement of the official page). According to the Japanese Wikipedia, it was founded in 709, and there are about 400 affiliated shrines. The complex comprises two sites: the upper shrine (上社), at 866 metres on Mount Akiha, and the lower shrine (下社), in the valley.
Shizuoka
https://theanimetrip.com/luoghi/santuario-principale-di-akiha