At least one person died climbing Mount Fuji days before the official start of the climbing season, and three bodies were found on the mountain, the police and local media said.

Among them was a professional rock climber, Keita Kurakami, according to Patagonia, which he was an ambassador for. He lost consciousness while ascending the mountain, Japan’s tallest, on Wednesday and was pronounced dead at a hospital, the local police said, according to public broadcaster NHK.

The three bodies were discovered about three-quarters of the way up the 12,400-foot mountain, all near its crater but in different locations, the local police said on Wednesday, according to NHK. It is unclear when the bodies were found. All three are thought to have been climbers who ascended separately, the broadcaster said.

For all of last year, seven Mount Fuji deaths were reported.

The police in Shizuoka Prefecture, where some trails to the summit start, started searching after a woman in Tokyo reported on Sunday that she had lost contact with her 53-year-old husband who had gone to climb Mount Fuji, the police said. He left on Friday evening and on Saturday, sent his family a photo taken near the summit but then fell out of contact, NHK said. The man was identified as one of the dead, Eriko Takahashi, the Shizuoka police department spokeswoman, said in an interview on Thursday.

The police were still identifying the two other bodies but suspected they were a man in his 30s who was reported missing in December and a man in his 50s who was reported missing in January, Ms. Takahashi said.

As Mount Fuji’s popularity has soared in recent years, officials have become more concerned about overcrowding and dangerous climbing practices.

There are four trails leading to the summit. The one in Yamanashi Prefecture opens July 1, and the three in the neighboring Shizuoka Prefecture open July 10, according to the mountain’s official climbing website.

Outside the summer climbing window, Mount Fuji experiences violent wind gusts and snowstorms, and climbers can fall because of the winds or slip on ice, according to the official climbing Mount Fuji website. Toilets and mountain huts where climbers can rest are closed in the off-season, according to the website for Yamanshi Prefecture police.

Authorities have long worried about climbers who try to ascend the summit without resting overnight at one of the huts that dot the trails. Climbing without breaks through the night can result in altitude sickness and hypothermia, officials have warned.

Mr. Kurakami, the professional climber, ascended the mountain from the Yamanshi trail, NHK reported. Patagonia said in a social media post that he had a heart attack in 2021, obtained treatment and continued climbing.

Although the number of people who summit the mountain has remained steady over the past decade at about 200,000 to 300,000 each year, the number of people who visit the start of the trails — and who might climb part of the way — increased from about three million in 2014 to five million in 2019, according to data from Yamanashi Prefecture.

This climbing season, Yamanashi Prefecture is for the first time capping the daily number of hikers and requiring hikers to pay a fee equivalent to about $12.50. It has also installed a gate at the start of its trail, which will be closed from 4 p.m. to 3 a.m.