Once upon a time, it said in this village as known as 'fusou village', there was a boy who has a demon power since he was born in this world. No one in that village knows why this boy has such power in early age, but there is one thing for sure, it's definitely a 'curse'. For such a rare event like this, all elders and people who an expert about demons gathering around and analyze this child's body, surprisingly they found one single mark on his left eye, they believe it was a kiss mark from certain demon, this child parents told them about what happened before give a birth. Someone wearing a black coat come to their house and suddenly attack them, gives a demon mark on pregnant woman's belly, and disappeared. After that event, 2 months later, the moment of giving a birth has come, but there was something weird happened, the demon mark on it's belly that remained 2 months ago disappeared and goes inside it's womb. After giving a birth, normally a baby will cry after come out from mother's womb, but this one is the weird one because this baby can't cry like normal baby does. The Doctor who helped this giving birth also surprised for this unusual event. Even in Medical studies, they never found such condition like this. After hearing this story from them, the elders and others also surprised and promised to investigate who a person with a black coat. They suspected of some certain group of people that they know very well, it was from Dark Arch Angel Organization. That organization is really dangerous because they have some power to brought demons in this world freely. All People in this world against them, that's why all village in Sekaido Region trained their finest young men and woman to fight them. All elders taught them how to deal with them in many centuries. This war between human and demon never stops ever since. And the big questioned is what destiny this boy awaits. who knows he might gonna use his demon power to defend humankind or the opposite. and this story begins...