Sun-ken Rock is a manga about Ken, a young Japanese man who follows his childhood crush, Yumi, to South Korea after she becomes a police officer. To win her over, he joins the local police force himself but is immediately assigned to a dangerous district run by a powerful mafia syndicate. After a series of violent events, Ken is forced to take over the gang and becomes the new boss of the Sun-ken Rock organization. The story follows his struggle to control the criminal underworld while maintaining his moral code and his relationship with Yumi. Readers enjoy it for its intense action, gritty urban setting, complex power struggles, and Ken's transformation from a lovesick boy into a ruthless leader.