The gameplay follows an interactive branching plot line with multiple scenarios, and focuses on the appeal of the four female main characters.

Much of the gameplay in The Devil on G-String requires little interaction from the player, because the majority of the time is spent reading the text that appears on the game's screen.

Though he acts kind and understanding in most social situations, this persona is a pretense used to hide his work as a highly intelligent and ruthless businessman.

As the president of one of his father Gonzō's corporations, Kyōsuke employs brutal—and often illegal—business tactics in order to pay off a massive debt accruing intense interest.

Due to Gonzō's abusive "education" and the severity of Kyōsuke's debt, he views money as the means, end, and purpose of life.

She can be considered a game-theoretical and observational genius as well as a musical prodigy, but her social skills are severely lacking, as evidenced by her awkwardly long, unkempt hair.

Due to his possible connection to yakuza turf wars, Gonzō instructs Kyōsuke to find and capture the enigmatic figure.

When "Maō" kidnaps the youngest child of the Miwa family and asks for an exorbitant sum as ransom, Kyōsuke helps the eldest, his classmate Tsubaki, obtain the necessary funds via a yakuza loan.

Depending on the player's choices, the Miwa family can be saved (granting an ending showing Tsubaki and Kyōsuke cohabitating years later) or forced to accept the developer's offer in order to repay their debt.

The third chapter of the game, "The Mephistopheles Murders", sees "Maō" take on an accomplice in order to kill people involved with Kanon Azai's skating career.

It is possible for the player to follow an alternate path in this chapter which sees Kanon and Kyōsuke build a romantic relationship, and portrays her figure skating career in a more detailed manner.

In the fourth chapter, "Blind Spot in Negotiations", one of Kyōsuke's classmates takes Mizuha Shiratori and a teacher hostage on the school grounds after hours.

Depending on the player's choices, this can be resolved quickly and segue into a romantic subchapter involving Mizuha, or can become a drawn-out affair which eventually leads to "Maō's" final plan.

In the latter case, Kyōsuke and his fellow yakuza surround the school while Yuki Tokita, with her extensive knowledge of the criminal mind, negotiates with the captor.

Surprisingly, the hostage scenario ends with the revelation that Yuki had enabled the captor to escape at the very beginning of negotiations, and was herself the mastermind behind the event in an attempt to financially ruin Mizuha's father.

Kyōhei informs the police that he will demand his army of trained mercenaries and rebellious youths to stand down pending the release of several criminals, including his father.

After a struggle and a chase, Haru nearly murders an unarmed Kyōhei out of rage; Kyōsuke takes the shot instead, in a selfless attempt to spare her from the guilt.

The limited edition contained an art collection from Akabeisoft2's previous titles Sharin no Kuni, Himawari no Shōjo, that game's fan disc Sharin no Kuni, Yūkyū no Shōnenshōjo, and Sono Yokogao o Mitsumeteshimau: A Profile Kanzenban, a desk calendar, and a demo of Tayutama: Kiss on my Deity from Akabeisoft2's sister brand Lump of Sugar released two months after The Devil on G-String.

The ending song, "Yuki no Hane, Toki no Kaze" (雪の羽 時の風), is performed by Barbarian On The Grove featuring Chata and is written and arranged by Bassy.