G-senjou no Maou - The Devil on G-String

You play as Azai Kyousuke, the son of an infamous gangster. Kyousuke knows what he likes and lets nothing stand in his way in getting what he wants. Referred to as God by his classmates, he often enjoys listening to Bach and "working" part time for his stepfather. But when a beautiful girl named Usami Haru appears in town along with an international criminal known as "Maou," they bring with them their cat-and-mouse game of plotting and intrigue.