There is an Ohkuma-yama in Toyama. I'm seeing a listing for one in Nagano, but I'm not entirely sure where. It does occur to me that Toyama and Nagano are right next to each other, so it may be the same mountain, just straddling the border. (Which, randomly, makes me wonder if that was the mountain where the helicopter crashed when I was out in Nagano...?)
Toyama Ohkuma-yama, with peaks labeled.
It appears to be located next to Mt. Tsurugi. *amusement*
And that is all the research for now, since I am sleepy.