@Heatisgood You are not considered an adult in The Republic of Korea AKA South Korea until you are 20 years old. So their 20 years old is our 18 years old. The 19+ would be similar to our NC17 rating, which is the actual rating for movie theaters if a movie contains s**, extreme gore, and graphic content (detailed depictions of child abuse would be NC17).
...because ✨MAGIC✨