Winter Sonata was probably the first k-drama watched by the majority of those who became k-drama addicts.
Typically, set in a high school love-theme, the sweet and innocent Yoo-jin falls in love with the newly transferred mysterious Joon-sang whose mathematical abilities and loner behaviour arises the curiosity of both teachers and students.
The love triangle plot then develops as Yoo-jin childhood’s best friend Sang-hyeok feels conquered by his platonic love to Yoo-jin and starts to question Joon-sang’s intention.
Joon-sang – son to a famous single-mom musician – is secretly searching for his biological father whom he doubts to be Sang-hyeok’s father (a smart math teacher at some college). The reason for his doubts is an old torn picture of his mom posing arm in arm with Sang-hyeok’s father, her school-time friend. This adds to the unease between Joon-sang and Sang-hyeok; for Joon-sang, Sang-hyeok could be the lucky boy who took his father from him; he could very possibly be his father’s son who was favored and beside which his father decided to stay and raise well.
The twist of events begins when Joon-sang gets into a car accident that leaves him in a coma after which he loses all his memories of his past life. His mom, who has been tortured every day by her son’s search for his unknown dad and his accusing words that subtly blames her for his shame of beginning an illegitimate son, is driven to fake his death and takes him away to the States, where she sets a whole new life for him with a new identity and a new name Min-hyeong. This deceitful act was rendered successful by the help of her psychologist friend who brainwashed Joon-sang’s faded memory and created a new one for him to recall.
Ten years later, Joon-sang becomes a successful architect who runs a company of his own. Ironically, his multi-national company seeks business in Korea, where Yoo-jin herself is a successful architect working on a project for Joon-sang’s company. Once they encounter each other, Yoo-jin is in a state of awe, that leads her to put off her engagement, and eventually cancel her marriage to her best friend Sang-hyeok who has been by her side for ten years now.
Tension arises when the relationship between Joon-sang’s mom and Sang-hyeok’s father is revealed. Joon-sang discovers that Yoo-jin’s deceased father had been a friend of his mom as well; he also recalls some conversation he had with his mom when she had declared to him that his father was a man she loved truly, but he left her and married someone else, and then died. Like fire, the shocking news that Joon-sang is Yoo-jin’s half-brother spreads all over damaging the hearts of not only Joon-sang and Yoo-jin but also their families and close friends. Luckily, Sang-hyeok’s father (who was in love with Joon-sang’s mom and has memories of their intimate relationship together ) is intrigued by this news; he wonders how Yoo-jin and Joo-sang are of the same age, although Joon-sang’s mother should have had conceived her baby earlier than Yoo-jin’s mom. After applying for a DNA test, the results were happy news to Joon-sang and Yoo-jin; Joon-sang was in fact his son; he was Sanghyeok’s half-brother after all. However, this update was really bad news for Sang-hyeok and his mom, the reason why Yoo-jin and Joon-sang could not stay together, for they decided to stand up for all the damage they caused and take responsibility for the hearts that got broken because of them. Sadly, Joon-sang had known of a tumor he had. He had to undergo a critical surgery that was going to either take his life,or take his eye-sight. Years later, Joon-sang – now blind – is reunited with Yoo-jin again after she coincidentally visits a house she found in some magazine that was just like that house that he has once promised to build.