Yuri, at the young age of 7, learned how to camouflage herself after her mother collapsed in a pile of blood, the bloody knife stabbed into her stomach...by her very own father. She ran away from home, and met a mysterious person, who changed her into a completely different person...a cold, heartless and emotionless killer. But who knows, under the numb heart was a warm and kind soul...that was waiting to be found by someone.

Many may think that melting her cold heart is almost impossible, she herself too. But not, until she receives a mission, which required her to protect four guys in a high school. The journey of reviving her warm heart...starts right there.