So it is a back story of the sin that kazuya's sister committed. After killing the murderes in order to avenge the death of his loved ones Wino is now living a quite life hidden from others. One day He saw a little girl who was alone in the streets of night. She doesn't seem to know the place where she is or from where she was. At first Wino was going to leave her be cause how will she be happy with a person like him but when he looked at her eyes trembled from fear and filled with darkness. He decided to take her with him,He enrolled her in a middle school and took care of her as his own little sister and their life's together was going happily! Till that day arrived. Today Miyaki(the girl Wino adopted) was going on a school trip with her class to visit a nearby shrine everything was going well until a girl and Miyaki got into an argument and the other girl slapped Miyaki and Miyaki fell off the hill everyone thought she died. Everyone from her class don't like Miyaki at all so to cover the evidence and to protect the other girl all the class sided with the other girl and told her it's not her fault that she fell off the hill and died she deserved that. All the class started cutting her body into pieces and then gave every student one peice to destroy. But there was another person who was present there it was Wino who camed to check on Miyaki on her trip and then what he saw the whole incident the murder of Miyaki he was so traumatized that his body won't move he lost another person who was dear to him. And guess who was the other girl it was Kazuya's sister.