We Promise Each Other in Life and Death, but We Will Depend on Each Other in the Next Life.

She and he were both killers, but they were destined to be enemies. In the dangerous situation, he fought to save her, and she fell in love with him. However, she could not violate the rules of the organization, so she chose to fight each other with swords. They fought many times, but they could not bear it. However, he did not abide by the rules of the organization and thought of her wholeheartedly, which ultimately led to a tragic ending.