The students were being trained in mountain climbing at a ski resort in the town of Nasu in Tochigi prefecture, about 120 miles north of Tokyo.
Forty other people were injured, including two who are in serious condition, authorities said.
The Japanese fire and disaster management agency said eight people were found with no vital signs, though they have not been formally confirmed dead by medical personnel.
Japanese media said they were students who were participating in a three-day training scheme for members of mountaineering clubs from seven schools in the area.
Heavy snow had fallen overnight, so a planned climb was cancelled and instead students were practising moving through heavy snow as mountain survival training.
One unidentified student told public broadcaster NHK that there was a strong wind and he could see a white mass heading toward him. An instructor told him to get down, and then everyone was engulfed.
Tochigi prefecture said 40 students and eight instructors were on the slope. Fourteen others in the group did not go out.
The ski season had ended at the resort.