We have good routes in alpine region from very easy one to extreme one. Most of areas can be reached within a few days from Tokyo, so it's a good option for weekend excursion during your business trip. Of course you can stay in the middle of mountains and indulge yourself in climbing for a while.
July - September
Hotaka, Tsurugi-dake, Kita-dake, Tanigawa-dake, Shakujo