Why did pilgrims climb Mount Fuji wearing white robes?

Pilgrims traditionally climbed Mount Fuji wearing white robes as a symbol of ritual purity.12

This practice is deeply rooted in the mountain's history as a site of religious devotion. From the Heian period onward, the mountain became associated with Shugen-dō, a tradition of mountain asceticism that blended Buddhism with indigenous beliefs. In this and other Japanese religious contexts, white garments are frequently used to signify purity and to help practitioners transition from the profane world to a state of contact with the sacred.123