The Strongest Mercenary: Chased by Dogs at the Beginning

A high school student was kidnapped by gangsters while traveling abroad with his family. Under the protection of his parents, he escaped with his sister, only to be surrounded by spotted hyenas. After going through many hardships and narrowly escaping from a hyena, he and his sister were captured and sent to a killer training camp. The brother and sister worked together to survive in the killer training camp. When the brother was seriously injured and dying, he was rescued by a passing mercenary group and volunteered to become a mercenary. Since then, there has been an invincible legend in the mercenary world.