Revenge (2005)

Seo Ha-eun (played by Eom Tae-woong) lost his father when he was 7 years old. He was brought up in Seo Jae-soo's house where he meets his love with Eun-ha (played by Han Ji-min), a pure, good-spirited person. Ha-eun ends up being a detective instead of a criminal. Ha-eun begins to unravel information about his dead father when he is investigating a suicide case. During the investigation, he discovers that he has a twin brother named Yoo Shin-hyuk (also portrayed by Eon Tae-woong), and meets him after 20 years. He also learns that his mother is still alive. The killers who wanted to assassinate Ha-eun accidentally murder Shin-hyuk, due to the similarities of the twins. Because of this, Ha-eun plans revenge by becoming Shin-hyuk.