Mr. Sakamoto, however, was not Korean, but Japanese. He went to work, in 1970, for a Japanese import/export company run by a Korean Japanese. This outfit did nearly all of its business with North Korea, and did quite well until the North Korean economy fell apart in the 1990s (because of the demise of the Soviet Union, and the end of Soviet subsidies.) His job gave Sakamoto legitimate opportunities to travel to North Korea (which has never been much of a tourist attraction). There, he spent many months being trained for his espionage duties. These later involved collecting information, from Japanese media, and Sakamotos own contacts, about Japanese attitudes towards North Korea, and other matters North Korean officials were curious about. He was also asked to send some items, like typical Japanese clothing, to North Korea (apparently to outfit North Korean agents sent to Japan.) What Sakamoto was doing was not really a secret. Japanese assumed that anyone working for companies that did a lot of business with North Korea, served the North Koreans in other ways. As a result, many journalists came to depend on Sakamoto for tips on what was really going on in North Korea. Sakamoto was often not sure himself, but he could give reporters more accurate information than was available anywhere else. Sometimes, the North Korean government would have Sakamoto leak specific information to Japanese journalists.
While Sakamoto never did anything illegal, he did know of other North Korean agents who apparently did. This involved stealing information, or paying people to do so. North Korean agents also kidnapped Japanese, and forced them to help train North Korean intelligence agents. This was not confirmed until 2002, although it was suspected for over a decade before that. Its also suspected that North Korean agents murdered Japanese Koreans who angered the North Korean government, and used other strong-arm tactics in Japanese. The Japanese government attributed this sort of thing to disputes between criminal gangs. Many of the gangsters in Japan are Koreans.
Sakamoto is said to be looking for a book deal.
Its no secret that North Korea has employed hundreds, perhaps thousands, of intelligence agents in Japan over the last half century. Now one of them has come forward and talked openly about his decades of spying. Using a false name (Sakamoto), the Japanese man actually did nothing illegal. Japanese law does not prohibit its citizens from doing intelligence collection for a foreign nation. And Japan has tolerated some questionable North Korean fund raising and intelligence operations because of the large Korean population in Japan. Those Koreans were first brought to Japan during the forty years (1905-45) Japan controlled the place. Most are Japanese citizens, but still identified as Korean no matter how well they speak Japanese. Just being born and raised in Japan does not make you a Japanese citizen. Many of these Japanese Koreans openly support North Korea, and back that up with financial, and other, support for North Korea.