From Easy Going Scans:

Lord Perdien is a 1st class demon who has been living in the human world with his son. He has no intentions for his son, Miryu, to follow the path of the demons and while their lives were peaceful up until now, a succubus arrival and a sudden illness of his son are more than enough to disturb their peaceful way of living. He has to make an important choice: Either to let his son die or listen to whatever the succubus offers him for a cure.