Japan's Hagoromo chalk continues its legacy in S. Korea english.kyodonews.net

Even in an age when whiteboards and computers are ubiquitous in classrooms, Hagoromo chalk has seen its popularity grow thanks to the huge market in the internet lecturing field in South Korea.
(Photo taken in Nov. 2015 in South Korea shows of Takayasu Watanabe (front row center) and workers at Sejongmall, now the sole producer of Hagoromo chalk.
Compared with ordinary chalk produced in South Korea, it was three times to five times more expensive.
Hagoromo chalk contains grinded oyster shells, among various other ingredients, said Shin.
I think Mr. Shin is doing that job (for Hagoromo chalk)," Watanabe, 75, said in a phone call with Kyodo News.