Cha Do Hyun is in line to be the successor of Seung Jin Group. No one in his family is aware that he's been suffering from dissociative identity disorder for years following a family tragedy. Oh Ri Jin is a first-year psychiatric student who runs into one of Do Hyun's many personalities while looking for one of her patients

Falling in love at first sight with Ri Jin, Se Ki vows to get rid of his host Do Hyun. Do Hyun looks for ways to make sure to keep his various personalities in check while he assimilates to life in Korea again

Do Hyun feels guilty when he finds out that he inadvertently put Ri Jin in danger because one of his alter egos. Ri Jin figures out the truth of his condition and sympathizes with him

Considering his instability a risk to himself and others, Do Hyun declines treatment and withdraws from people and work. Seung Jin Group harbors a deep family secret kept hidden from Do Hyun, who also discovers a new personality has emerged

Unable to tell Do Hyun and his other personalities apart, Ri Jin gets confused about who she's beginning to have feelings for. Do Hyun is warned that Se Ki's personality is growing stronger

Do-hyun enlists Ri-jin as his personal doctor to prevent the Se Ki personality from completely overtaking him. ID Enter is on the hunt for clues about Writer Omega's identity.