Was the Joseon warrior Baek Dong-su a real person?

Half true, half false.
In sword fighting, neither China nor Joseon could defeat the Japanese warriors.
The swordsmanship of the Japanese warriors, who had gone through a century of the Sengoku period, was superhuman.
Would you believe it if I told you there were hundreds of Joseon people who crossed over to Japan to learn it?
After enduring all sorts of hardships, how many of them actually survived to return to Joseon and continued to develop their skills to become the swords of Joseon?
Baek Dong-su lived roughly during the era of King Jeongjo,
and at around 50 years old, he was considered an old man for that time, not a young man.
He is half a historical figure and half a legendary figure.