A Japanese adult visual novel, G-Senjou no Maou (translates to English as "The Devil on G-string," a play-on-words between both August Wilhelmj's adaptation of Bach, "Air on the G String," and Franz Schubert's "Der Erlkonig") is a crime thriller in which the player takes the role of Kyousuke Azai, a teenage boy who is adopted and employed by a yakuza leader in order to pay off the debts incurred against his family after a tragic incident that caused his father to be incarcerated and left his mother and him in poverty. A cunning, business-minded individual, Kyousuke is highly competent in managing businesses subordinate to his father's yakuza and makes a living and slowly pay off his family's debt as a result of this work, which forces him to value money above all.
Despite having successfully managed his school life on top of secretly administrating businesses under the yakuza, his identity and illicit lifestyle is on the verge of being compromised by a long-standing conflict between an eccentric young, self-proclaimed detective named Usami Haru and an enigmatic criminal mastermind who goes by the alias "Maou."
While the barriers between his school life and criminal affiliations start to break down as Maou begins to target those around him, Kyousuke Azai must ally with Usami Haru in order to confront Maou and uncover his true identity.
Usami Haru is the primary heroine of the overarching plot, but there are three other heroines with which the player may choose to elope depending on player choices.
This game was developed by Akabeisoft2.