She met him that year when she was three years old and he was five years old. She gave him his parents' wedding ring and said that we are engaged and you can't like other girls in the future.
She has always kept her vows, she just waits for him to marry her.
When he was twenty years old, he originally lived only for revenge, but he met her again. Unexpectedly, she recognized him at a glance after not seeing him for fifteen years. Only then did he know that she had always kept their vows.
He joined the killer organization for revenge and could not have any feelings, but he could not let go of her who made a vow to him when she was five years old.
Should he leave her who has been chasing him so hard, or should he give up his hatred and lead her away.