Smart and promising medical student Kang Ma-ru is deeply in love with his slightly older neighbor Han Jae-hee, a television reporter. But when her situation takes a turn for the worse and Jae-hee becomes desperate to escape poverty, she meets a man who changes everything—a rich CEO who introduces her to a life of comfort. So she turns her back on Ma-ru, choosing money over love. The brutal betrayal leaves Ma-ru fractured—not just angry, but a completely changed man. A few years later, Ma-ru is now 30 years old and works as a bartender and gigolo, no longer a "nice guy." He then meets Seo Eun-gi, a young chaebol heiress who's being groomed to take over her father's conglomerate. Eun-gi is cold and calculating, business-savvy, and raised by her father to never show emotion to anyone. Ma-ru decides to take revenge on his ex Jae-hee and bring her down from her position after his sister, Kang Cho-co is rushed to the hospital because of Jae-hee. Ma-ru, though initially had no plans as such, uses Eun-gi to take revenge on Jae-hee Just when Ma-ru is beginning to love and care for Eun-gi, she finds out the real reason why he approached her and they break up. But a car accident causes Eun-gi to lose her memory, and she enters Ma-ru's life again.
Cast
Main
Song Joong-ki as Kang Ma-ru, a smart but poor medical student who has to look after his little sister without any parents. He was in love Jae-hee but she left him for a rich CEO as she always dreamt of being rich, but she always loved Ma-ru and still harbours feelings for him. Six years after Jae-her left he became arrogant and a playboy who works as a bartender. He approached Eun-gi as part of his revenge plan against Jae-hee but he started to care for her and eventually fell in love.
*Kang Chan-hee as young Kang Ma-ru
Moon Chae-won as Seo Eun-gi, a rich and arrogant girl but also has a kind-hearted side who does everything to protect her mother's memories who has a troubled relationship with her father and step-mother as she blames them for her mother leaving and her death. She falls for Ma-ru without knowing the real reason he approached her and she suffers a memory loss after landing in a car accident. After her memory loss, she is a much nicer person who searches for clues in order to get her memory returned
Park Si-yeon as Han Jae-hee, although she is stone-hearted and loves Ma-ru,she loved money more than Ma-Ru and she left Ma-ru and became the mistress of CEO and had his son. Although, her and Eun-gi don’t get along and she also dont care for her and tried to hurt her in many ways. She plans to take over Taesan Company after killing her husband.
*Park So-young as young Han Jae-hee
Supporting
Lee Kwang-soo as Park Jae-gil, Ma-ru’s best friend and Choco’s lover
Lee Yu-bi as Kang Choco, Ma-ru’s younger sister and Jae-gil’s lover
*Han Seo-jin as young Kang Choco
Lee Sang-yeob as Park Joon-ha, Eun-gi’s secretary and helper who loved and respected her.
Kim Tae-hoon as Ahn Min-young, the secretary of the CEO who likes Jae-hee.
Yang Ik-joon as Han Jae-sik, Jae-hee’s older brother who was abusive towards her.
Kim Yeong-cheol as CEO Seo Jung-gyu, Eun-gi and Eun-Seok’s father, who found Jae-hee and took her as his mistress. Although, good hearted he sides with Jae-hee rather than his daughter as Eun-gi is stubborn and act childish at times. He dies later in the season and gives his property and estate to Eun-gi but before she could be in charge she lands in a car accident and suffers a memory loss.
Jin Kyung as Hyun Jung-hwa, Eun-go’s assistant. After the car accident which caused Eun-gi’s memory loss she took her away and cared for her for a year where nobody could find her.
Oh Yong as Jo Young-bae
Jo Hwi-joon as Seo Eun-seok, Jae-hee and CEO’s son, Eun-gi’s 4 year old step-brother who he loves despite her rudeness and hatred to him but after her memory loss she is unable to remember about her hatred for him and instead grows closer to him
