Kim Do Hyun

Yoon Hyun Woo is a devoted, hard-working, and loyal secretary to the Soonyang chaebol family, which runs the lucrative Soonyang Group business empire, founded by Jin Yang Cheol. During a power struggle between Jin Yang Cheol's children for control of the empire, Hyun Woo is ruthlessly betrayed and killed under the orders of an unknown member of the chaebol family. Miraculously he wakes up as a kid inside the body of the youngest member of the family – Jin Do Jun. After he realizes what has happened, Yoon Hyun Wo plots to use his new “identity” to formulate a hostile takeover of the group – and punish the people who killed him. But, will the cold-blooded and money-hungry CEO of Soonyang Group, one who firmly believes in right of primogeniture, be so easy to win over or conquer? Will Hyun Woo be able to wrest the reins from Jin Yang Cheol's children? And what role will be played in all this by a dogged public prosecutor named Seo Min Young, nicknamed “Soonyang Group Grim Reaper”? (Source: LuckyGirlGwenIce at MyDramaList) ~~ Adapted from the web novel "Youngest Son of a Conglomerate" (재벌집 막내아들) by San Gyung (산경).

A series of disappearances take place in Gangnam, Seoul. Jae Hui works for a famous bar in Gangnam and she knows a secret involving the series of disappearances, but she also disappears. People who become involved with the case include Detective Kang Dong U, who was demoted and then returned to work, Gangnam outlaw Yun Gil Ho, who put himself on the list of suspects, and Prosecutor Min Seo Jin, who works on this case as an opportunity to raise her status. They chase after the truth of the case for different reasons. (Source: AsianWiki)

Byun Moo Jin was married to Geum Ae Yeon. They had a daughter, Byun Mi Rae, and a son, Byun Hyun Jae, during their marriage. Moo Jin attempted various business ventures while married, but they all failed. His family could not take him anymore, and they cut him off from them. After going through a divorce, Ae Yeon experienced difficulties raising her two children by herself. Now, 11 years later, she works part-time at a big mart. Her daughter and son are all grown up. The daughter, Mi Rae, wanted to become a person her mother could rely on. She works as the MD at a big mart. She is also the breadwinner of the family. The son, Hyun Jae, has a unique charm, but he is also the troublemaker of the family. One day, Moo Jin appears in front of his family as the owner of the villa building where they live. Moo Jin hopes to reunite with his beloved ex-wife Ae Yeon and even tries to seduce her, but the daughter, Mi Rae, is strongly opposed to her father's idea. Unlike his sister, Hyun Jae supports his dad's attempt at reconciliation. Meanwhile, Mi Rae gets involved with Nam Tae Pyung. He was once a member of the national taekwondo team and now works as a security guard at the same mart as Mi Rae. He hides his real identity and the fact that his father owns the mart. (Source: AsianWiki)