Saeko is in a romantic relationship with Yusuke. Her boyfriend proposes to her, but, on that same day, he gets into a car accident and dies. Saeko falls into deep despair after his death. A few months later, she meets a man named Naruse. Although unaware at the time, Naruse received a heart transplant from Yusuke and he feels something for Saeko in his heart. (Source: AsianWiki)