The ace killer, in his first and last mistake, died for love. But he strangely transformed into his six-year-old self. In the grief of leaving his beloved, he got a long-awaited happy family. But for some reason, the people she cares about are leaving her one by one. She has been hit hard many times. Should she lose her goals and surrender, or regain her dreams and move forward bravely? Can she still meet him in her heart...