Yi Sun-sin was a very important person in history. He was from Korea, which is a country in Asia. He lived a long time ago in the 1500s, but people still talk about him today because he did some really amazing things.
Yi Sun-sin was a general in the Korean army. This means he was in charge of a lot of soldiers who fought in battles. He was really good at his job and won many battles.
One of the most important battles that Yi Sun-sin fought was against the Japanese. The Japanese were trying to take over Korea, but Yi Sun-sin and his soldiers fought really hard to protect their country. Yi Sun-sin was very smart and came up with clever strategies to defeat the Japanese.
One of the things that made Yi Sun-sin so special was that he invented a really cool ship called a turtle ship. This ship was really strong and fast and had armor on it to protect the soldiers inside from enemy attacks.
Yi Sun-sin was a hero to many people in Korea. He was brave and did whatever he could to protect his country. Even though he died a long time ago, people still remember him today and look up to him as a great leader.