Teenage Mercenary

Nyuugaku Youhei is the Japanese title of Mercenary Enrollment, also known as Teenage Mercenary, a very popular Korean webtoon. A webtoon is a comic made to be read by scrolling down on a phone. The series is written by YC and drawn by the artist rakhyun. It started on Naver Webtoon in Korea in 2020, and in Japan it has run on the LINE Manga app since April 2021. It topped LINE Manga's yearly rankings in both 2023 and 2024, and by May 2025 it had more than 1.86 billion views around the world, in ten languages. The anime version was announced in June 2025.

The hero is Ijin Yu. When he is only eight years old, he loses his mother and father when their airplane goes down. He is left alone, far from his home country. To stay alive, the little boy grows up as a soldier who fights for money. For ten years he lives this hard life. He learns to fight, to plan, and to stay calm in danger.

Then Ijin finally goes back to Korea and meets his family again. Suddenly his life is quiet. There is plenty of food, a safe place to sleep, and peace all around him. But there is one more year of school left for him to finish. For someone who grew up as a soldier, a Korean classroom is a strange new world. He does not know many of the normal social rules that other teenagers learned growing up.

The school soon shows its own dangers. Bullying is one of the main themes of the series, and there are students who hurt others because they think no one will stop them. Ijin will not let that go. When trouble comes, he deals with it using the calm skills of a trained fighter. Much of the fun is watching troublemakers pick on the new student, only to learn they have made a big mistake. The story jokes that the real question is not whether Ijin can get through a year of school, but whether the school can get through a year of him.

The themes listed for the series include military life, martial arts, school, bullying, and even acting. Under the action, there is also a softer story about a young man who lost his childhood and must learn how to be a normal teenager and live with his family again. The genres are action and drama.

For fans of the webtoon, the big draw is seeing Ijin's fight scenes animated. For new viewers, it is an easy-to-follow action story with a simple, strong hook: a quiet young man with a hard past who stands up to bullies.