Fuji Rock Festival takes place in Yuzawa, Niigata, Japan, usually in July, Japanese summer. It is a 100,000-capacity festival, running 3 days across mountain with camping on site.
A ski resort in rainy season: the site is a mountainside, the walk between stages is a genuine hike, and the crowd wears technical outdoor gear as fashion. Rain ponchos are near-universal.
Days sit around 26°C (79°F) and nights fall to 16°C (61°F), a 10-degree swing that most first-timers underestimate. Rain is likely at some point across the weekend. Combined with the ground here, that means mud, which is the single biggest factor in what you should put on your feet.
Below: the 10 outfits that work best at Fuji Rock Festival, what the crowd actually wears, and the practical rules, bag size, footwear, night layers. That decide whether the outfit survives the weekend.