Deus Machina Demonbane

Kurō Daijūji is a private detective in Arkham City, down on his luck and dead broke. He gets an offer of work from the Hadō Financial Group to track down a magic book. He turns down the offer at first, until he sees the more-than-handsome reward they are offering upon completion. Not long after, he runs into a small girl named Al Azif, who is in fact a powerful grimoire. The two of them form a contract, with Al Azif granting Kurō powerful magic, and soon after activating a powerful giant mecha known as Demonbane. The two of them will need to go up against a mysterious mechanical menace known as the Black Lodge.

Demonbane is an erotic visual novel which combines the giant robot and transforming hero genres with elements of the Cthulhu mythos. It plays like a standard visual novel, with little interaction apart from occasional dialogue choices, leading to one of seven different endings.

Initial Japanese PC releases included randomly-selected telephone cards; two with the limited edition, one with the first print regular edition. The PS2 release removes all of the adult content, features completely redone voice acting with a new cast, and includes a 1-episode anime OVA.