Hi MacNara,
Thank you for your well-argued response. I am aware of the limitations but one has to try, even though there was no success. If not, I will visit Karuizawa anyway, with risk of focusing on a wrong area there.
It has not been a total blank, though. Private messages are not shown here. A BirdForum friend will soon visit Mt. Fuji area to have a look on the situation in the field.
Guides are not my thing, even though I occasionally guide myself, for free. I only need to know the general area where to go and will then search for the birds by myself. It is more rewarding that way.