(빅)is a June 4 - July 24, 2012 TV series directed by Ji Byung-Hyun,
18-year-old Kang Gyung-Joon's (Shin Won-Ho ) spirit suddenly finds itself in the body of 30-year-old Seo Yoon Jae ( Gong Yoo ) . Seo-Yon-Jae is a successful doctor and engaged to high school teacher Gil Da-Ran ( Lee Min-Jung ). Gil Da-Ran just so happens to be the teacher of 18-year old Kang Gyung-Joon. More problems ensue when 30-year-old Seo Yoon Jae falls in love with another woman ( Bae Suzy ).
Da-Ran ( Lee Min-Jung ), currently preparing to take for her teacher's exam, goes to a wedding hall to deliver a bouquet. When she hands over the bouquet Da-Ran discovers the bride is a friend of hers. Da-Ran also makes the uncomfortable realization that she wasn't invited to her friend's wedding. She stays at the wedding and gives money to the couple as a wedding gift. Da-Ran then eats lunch at the wedding alone. She then receives a phone call that the bouquet was delivered to the wrong bride and she needs to get it back. Da-Ran attempts to catch the bouquet at the end of the wedding, but bumps into a man named Yoon-Jae ( Gong Yoo ). Due to the bump, Da-Ran falls down the stairs and is hospitalized. As fate has it, her doctor at the hospital is Yoon-Jae, the man she bumped into at the wedding. Their relationship develops into a romantic relationship and one month later they plan to get married.
Now, Da-Ran works as a temporary teacher at a high school, while preparing for her exam to become a teacher. When she goes to work on the bus, she listens to her own story that she wrote in to the radio station. Da-Ran gets off the bus and a young man Gyung-Joon ( Shin Won-Ho ) gets off at the same bus stop. Da-Ran mistakenly believes the young man likes her. It turns out that Da-Ran took his umbrella on the bus and Gyung-Joon is a student at the high school where she works. High school student Gyung-Joon lived in the United States with his mother, but after his mother died came back to South Korea.
Da-Ran's wedding approaches and she is excited, but Yoon-Jae acts differently. Yoon-Jae seems to be avoiding Da-Ran. On the day they are to look for a new home, Yoon-Jae calls that he can't make it and Da-Ran bursts into tears. She asks if Yoon-Jae really loves her or just feels responsible for her and then hangs up. She doesn't know what to do. Then, her student Gyung-Joon sees her and takes her on a ride on his motorcycle. They go out to a lake, outside of Seoul. While looking at the water, Yoon-Jae calls Da-Ran and tells her that he will give her the answer to her question. Meanwhile, Gyung-Joon gets back on his motorcycle and leaves.
Yoon-Jae drives out to meet Da-Ran by the lake. Meanwhile, Gyung-Joon is leaving the area on his motorcycle. As the two approach each other, an accident occurs in front of them. They both try to avoid the car crash and both drive into the water.
As Yoon-Jae's car sinks deeper into the water, he manages to get out of the car, but sees high school student Gyung-Joon sinking past him. Yoon-Jae grabs him and goes back up to the surface.
At the hospital, Yoon-Jae is declared dead. Da-Ran rushes to the hospital and cries in front of the hospital mortuary. Then, Yoon-Jae suddenly wakes up. When he sees himself in the mirror he is shocked. He has Yoon-Jae's body, but his mind is that of high school student Gyung-Joon. He walks out of the mortuary and sees Da-Ran crying in the hallway. Da-Ran is so happy to see Yoon-Jae alive, but he insists that he is Gyung-Joon. Gyung-Joon then wonders where his body is and finds that his body is unconscious and in the hospital. Gyung-Joon starts to panic and walks out of the hospital.
Da-Ran finds out Gyung-Joon's address and goes there. She finds Yoon-Jae's body laying down in the high school student's bed. She realizes that Gyun-Joon's mind is indeed in the body of her fiance Yoon-Jae.