Well-known Hosei University professor Naoki Ogi, who taught 10 students involved in last Friday's ski bus crash has slammed the government for allowing the "horribly managed" company to stay in business.

Ogi, who is known by his nickname "Ogi Mama," which comes from his warm and gentle character, also paid tribute to those killed in the accident in Karuizawa and spoke of the difficult path ahead for the injured survivors.

The crash, which killed 15 people and left more than 20 injured, claimed the lives of four Hosei University students.