Who is Yuki Imai, the Japanese journalist Russia has arrested on espionage charges?

A Japanese journalist has been detained on suspicion of espionage on Sakhalin, Russia’s Federal Security Service (FSB) said. The agency identified him as a Japanese national and a correspondent for the newspaper Hokkaido Shimbun but did not release his name. He was detained in Yuzhno-Sakhalinsk shortly before he planned to leave Russia and taken to Moscow.