Live peacefully as siblings, Yoon Joon and Yoon Eun-shoo-shoo think if they'd always been together as brother and sister. However, an incident that occurred when Eun-suh has an accident changed everything.
From the test results, the new discovery shoo if blood-Eun and her parents turned out to have different classes, which means she comes from another family. Later revelations, while Eun-born baby shoo confused with another woman who has grown into a teenage girl named Choi Shin-ae.
After the fact was revealed, the enemy and Shin Eun-ae switch places. Yoon own family eventually moved to America, so Eun-enemy who lives alone with his mother from a poor family. Of course, not easily adjust to new life.
Does not feel 10 years have passed, and Joon-suh returned to Korea to find his biological brother who has become a beautiful woman. Both meetings plus childhood memories make them fall in love, but love is not easy to unite them.
Because, Eun-suh already has a boyfriend a nice young man named Tae-suk Han Joon-enemy while has also been engaged by Shin Yu-mi. In addition, parents also opposed to each of these relationships because they had been living as siblings.
However, they remain desperate to continue the relationship 'forbidden love' and the new changes because one thing: Yoon Eun-malignant enemy turned out to have cancer. Until entering the last moment of her life, she was trying to hide her illness from the man she loved them.