There are ski and snowboard shops in Fukushima, Koriyama, Inawashiro and Aizuwakamatsu. If you need to rent your ski or snowboarding gear, you can do so at the ski resorts. There are also rental shops on the approach to Mt Bandai in Inawashiro.
Nekoma has a Burton Step On Test Ride Center and a Vector Glide demo center. They also have waxing and tuning services at Fun Ride+.
Inawashiro Snow Paradise has a Burton Learn to Ride rental center.
Bandai Rental at the Bandai roadside station has ski & snowboard hire. They offer full tuning / waxing and quick wax services.
Crib Inawashiro has complete premium snowboard gear and apparel for rent.
East Japan rental in Inawashiro has skiing and snowboarding equipment for rent. They also do tuning and maintenance services.
Safe Tourism a travel agency in Inawashiro also has rental gear during the ski season.
There are Xebio super sports stores in Fukushima city and AizuWakamatsu. These are general sports stores which will have ski and snowboard gear in Winter.
Mallard is a snowboard focussed shop with locations in Fukushima and Koriyama. They sell a full range of snowboard gear including Japanese made powder boards from MOSS, TJ Brand and Gentemstick. Mallard also offers tuning / waxing services.
Post is a skate / snowboard shop in Koriyama. There is an outdoor mini skate park if you would like to pop some tricks.