North Korean "ghost ships" had previously washed ashore from time to time, but the sudden spike over the last month - there were a record 28 in November, compared with only four the previous November, according to the coast guard - has many people here wondering what is going on? And does it tell us something about the state of North Korea?
As with so many things about North Korea, it's difficult to know for sure. But many analysts think it's a reflection of food shortages, which in turn are the result of tougher sanctions on North Korea imposed to punish the regime for its continued nuclear defiance.
"North Korean fishermen have to work harder than ever before and they have to go further out into the sea, but they don't have new boats," said Atsuhito Isozaki, associate professor of North Korean studies at Keio University.
Most of the boats washed up in Japan are about 32 feet long and wooden so they have trouble withstanding the rough winter seas. Many of the bodies are decomposed or just skeletons, likely a reflection of the storms and difficult seas in the area in October.
"Plus, North Korea doesn't have enough gasoline anymore so they're running out of fuel," Isozaki said.
North Korean leader Kim Jong Un has been aggressively promoting fishing as a growth industry and started this year by ordering a "dynamic drive for catching fish" with "modern fishing vessels."
"Fishing boats are like warships, protecting the people and the motherland. Fish are like bullets and artillery shells," the Rodong Sinmun, the official newspaper of the ruling Workers' Party, wrote in an editorial last month. Winter fishing was an "important battle" to meet annual seafood quotas, the paper said.
North Korea's seafood exports to China grew by a whopping 75 percent between 2015 and 2016, hitting $190 million last year, according to figures from the South's trade promotion agency. This made it one of North Korea's biggest sources of revenue.
But in August, in response to the launch of North Korea's first intercontinental ballistic missiles, the U.N. Security Council banned seafood exports from the rogue state. The following month it slapped limits on the amount of refined petroleum products that could be exported to North Korea, all part of a strategy to make the regime think twice about pursuing nuclear weapons.
While it is still too early to see the full effect of those sanctions - and the extent to which neighboring China is implementing them - analysts said they do appear to be causing North Korea some pain already.
"Fishermen usually have a set quota and they used to sell the seafood to China," said Toshimitsu Shigemura, emeritus professor at Waseda University. "Now with the new sanctions, they can't sell the seafood overseas but the quota still exists so fishermen need to go fishing. They probably stay out too long to catch more fish."
North Korea is reported to have sold the fishing rights along its coast to China so, to meet their quotas, North Koreans appear to be fishing illegally in the Yamato shallows, a rich fishing ground inside Japan's exclusive economic zone. If they run out of fuel, the strong northwesterly winds from China will blow them towards the Japanese coast.
Others say the increasing number of fishermen washing up in Japan might be evidence of food shortages in North Korea, with fishermen pushing themselves to extremes in search of a good catch.
"The food situation is getting worse, so fishing is encouraged in order to fulfill people's needs," said Sotetsu Ri, a North Korea expert at Ryukoku University. "Fishing is one way to deal with the economic situation."
The Mainichi Shimbun, a left-leaning Japanese newspaper, said that the sudden spurt in "ghost ships" showed the tyranny of the North Korean regime.
"The Kim administration says that its policy focus is on nuclear development and improving the lives of its citizens," it wrote in an editorial this week. "But in reality, the administration's policy of nuclear and missile development has led to the deterioration of the lives of the North Korean public, forcing them to undertake ill-advised fishing excursions."
Not all the boats have contained corpses. A total of 42 men have been found alive, with one boatload of eight telling Japanese authorities they were looking for squid when their engine failed.
In another incident, 10 North Korean men sought shelter in a hut on an uninhabited islet in northern Japan. But after they broke in, they stole a TV, refrigerator and rice cooker. When the Japan Coast Guard spotted their wooden boat, the men dumped the appliances into the sea.
All of the men found in recent weeks have asked to be returned to North Korea and the Japanese government is in the process of sending them back
The arrival of North Koreans is causing jitters along the coastline, the same stretch of land from which Japanese citizens were abducted by North Korea in the 1970s and 1980s.
"It doesn't really make us feel great," said Kazuhiro Asai, head of the Oga branch office of the Akita Fisheries' Cooperative Association, located near where eight men were found alive recently.
"In the past, there was a case where North Koreans came to kidnap someone nearby and that was scary. I guess these guys aren't out to kidnap but we don't know what they're here for and that makes me worried."
For others along the coast, where North Korea has been landing many of its missiles in the water, this is another unwelcome encroachment from a hostile neighbor.
"We have an uneasy feeling," said Sakari Nishimura of Yamagata Prefectural Fisheries' Cooperative Association. "These days we not only need to watch out for missiles falling from the sky, now we have to watch out on the sea, too."
