Late oct is a good time to head into the japanese mtns as not many folks around and skies are clearer than summer mths. If you're on your own I would aim to do the Yari Hodaka traverse (start point Kamikochi), it's basically a fun 3 day scramble on some of japan's biggest and most impressive mtns. If you have a partner/are a competent alpine soloist you could spice it up a little by:
- Starting it by taking the n ridge of yari route, although maybe expensive for you to get to start of route due to remoteness.
- Starting/finishing on myo jin san
- Including an ascent of mae hodaka north east ridge.
Unfortunately there are no english alpine/rock climbing guides. If you are willing to buy a japanese one, i'll later post a amazon link.
Other big (3000m ish)peaks that offer rock routes are Kita dake (n buttress), Hodaka, Tsurugi dake and nearer to tokyo Aka dake in the yatsu ga take range.