Renting your gear is easy in Hakuba. All resorts have rental centers, but if you want to visit several ski fields, its best to rent off-mountain. There are lots of rental stations around the village and at the base of resorts. Most of them have multilingual staff. The 2 big names Spicy & Rhythm have multiple locations around Hakuba. Rhythm even offers free pickups / drop offs and a paid courier return service.
If you are looking for Japanese powder boards check out roundAbout near Hakuba station. They are an independent local snowboard shop and a demo center for MOSS snowstick one of the original powsurfing companies.
VEX Select Museum is another local store focussed on the culture of powder riding. They carry Japanese branded gear, snowskates and nice looking apparel you can only find in Japan.
Fullmarks Hakuba carries a select line of outerwear and accessories. They also stock the skis and boards from Vector Glide - a premium domestic brand.
Material Sports is a ski specialist and carries the entire line of ID One skis - a brand which has been rocking the racing world.