Kurou is a poor detective living in Arkham City. One day, he was requested by Ruri of Hadou Financial Group, to search for a magic book. While he initially refused, Ruri offered him a large sum of money upon completion of her request, in which bribed Kurou to accept. As Kurou searches for the book, he runs into Al, a pretty girl that is actually a powerful grimoire. They forge a contract with each other, bestowing Kurou with powerful magic and Demonbane, a deus machina. (wikipedia.org).