Often described as “the Rolls Royce of chalk,” Hagoromo once faced extinction in 2015, but the brand managed to survive after a former cram school teacher in South Korea took it over, importing the manufacturing know-how and equipment from Japan.

In a factory in Pocheon, about 50 km from Seoul, 15 employees work tirelessly to produce the chalk with “Hagoromo” printed on the side of each piece.

“Orders from China are so large that our deliveries are getting delayed, and it’s not like we can upgrade the machines to produce more as they’re the exact machines that were brought over from Japan,” said Shin Hyeong-seok, CEO of Sejongmall Co., now the sole producer of Hagoromo.

Orders from all over the world skyrocketed after a video clip titled “Chalk of Champions” was posted on YouTube showing several mathematics professors praising how perfect Hagoromo chalk is — one even going so far as to say its special ingredient must be “angel tears.”

Since it was posted on May 2, the clip has garnered almost 10 million views.

Indeed, teachers around the world love the brand as the chalk writes smoothly without having to press hard on the blackboard, is clearly visible, erases well, does not leave dusty residue on the hands and holds up through lectures without breaking.

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. The chalk grabs students’ attention with its crisp, fluorescent colors, Shin explained.

Founded originally as Nihon Chalk Seizosho (Japan Chalk Factory) in 1932 in Nagoya, Hagoromo Bungu (Hagoromo Stationery) had been in the same family for three generations when Takayasu Watanabe, grandson of the founder, decided in 2014 to close the business due to poor health and the absence of a successor.

Shin, who had forged a relationship of trust and confidence with Watanabe for more than 10 years, said he offered to take over the business since he had always been over the moon about the premium chalk, which he used as a cram school teacher.

“But it was very, very difficult to get things started at the beginning,” the 49-year-old said, recalling those early days.

To bring all the machines over from Nagoya, 16 shipping containers had to be used. Importing and reinstalling them cost him nearly 10 billion won ($851,063).

For example, due to the difference in voltage, which is 100 volts in Japan and 220 volts in South Korea, he had to rework the entire electrical system to power up the machines.

“If I were to go back (in time) I don’t think I’d make such a choice,” Shin said with a laugh.

Another problem that emerged was the cost of producing the high-end chalk. Compared with ordinary chalk in South Korea, it was three to five times more expensive.

Shin, however, chose to highlight the quality of Hagoromo instead of changing the ingredients to bring the price down. Hagoromo contains ground up oyster shells and other materials, Shin said.

Shin sent samples to nearby schools with a description attached that said, “the best weapon that a teacher can take into classes.” As a result of his hard work, the company posted sales of nearly 10 billion won last year. It expects to post record sales this year.

Given his long relationship with Japan, Shin expressed deep concern about the state of bilateral ties, which have sunk to their lowest level since they were normalized in 1965, amid disputes stemming from Japan’s 1910-1945 colonial rule of the Korean Peninsula.

“I understand that there are historical problems that the two countries share,” Shin said, emphasizing the need to overcome them by building trust through interaction, just as he did with Watanabe.

The former head of Hagoromo said that he, too, hopes Japan and South Korea will find ways to maintain good relations.

“Politics is politics, but other things have to go on. I think Mr. Shin is doing that job (for Hagoromo chalk),” Watanabe, 75, said in a phone call with Kyodo News.

Shin said he clearly remembers the day he saw a comment on the internet about a story that had a picture of Watanabe carefully checking a chalk-making machine when he visited Seoul in 2015.

Some of the comments said the story about Shin and Watanabe should be made into a movie so that more people can learn about it.

Shin said he was moved by the suggestion.

“I will put my best effort possible into making chalk and continuing the business so that Watanabe-san can feel proud,” Shin said as he went back to a machine churning out freshly made chalk.