After witnessing his twin brother Na-Jin's murder, Na-Gyunn decides to seek vengeance by masquerading as Na-Jin. Despite their resemblance, Na-Gyunn lacks Na-Jin's fighting prowess. To achieve his goal, Na-Gyunn commits to honing his skills to match his brother's. The question looms: can Na-Gyunn maintain his charade without arousing suspicion from those around him?