RapeLay (レイプレイ, Reipurei) is a 3D eroge video game made by Illusion, released on April 21, 2006, in Japan. Compared to Illusion's previous games, the main story is shorter, features an improved 3D engine and is mainly played through mouse control. The game centers on a vengeful repeat offender who stalks and rapes a mother and her two daughters. Three years after its initial release, the game garnered international attention and controversy for its content, resulting in it being banned in several countries.

RapeLay is played from the perspective of a recently-bailed chikan named Masaya Kimura, a recidivist sex offender who has a history of previous arrests and also happens to be the son of a high-rank public official. With his release, he stalks and subsequently rapes the Kiryū family: a widowed 42-year-old mother named Yūko and her two daughters 17-year-old Aoi and 12-year-old Manaka.

The game's Story Mode centers around Kimura who rapes (in consecutive order) Manaka, Yūko, and Aoi. After the player finishes raping all three women, they unlock Free Play mode, where the player can engage in consensual sex with the same three women in a variety of selectable stages.

Aoi Kiryū catches Masaya Kimura groping a woman on a subway train, leading to his arrest by the authorities. The next morning, she and her younger sister Manaka help their mother, Yūko, find a wallet she lost around their home while talking about Aoi's incident the previous day. Unknown to them, a recently released Kimura secretly eavesdrops on their conversation while waiting outside their house; he reveals that his father, a well-known influential politician, managed to bail him. When Kimura discovers that Yūko is widowed, he decides to exact revenge, starting with Manaka.

After following Manaka to the subway station, he gropes her on a train. Leaving the train at the next stop, he traps Manaka in a public bathroom, rapes her and takes photos of her naked, semen-covered body with his mobile phone. Masaya instructs Manaka to feign sickness and stay in her room the next day.

The following day, Masaya follows Yūko from her house to the subway before fondling her on a train. He then follows her to the city park. As instructed by Masaya, Manaka calls Yūko on her mobile phone, telling her that she is in the bushes at the park. When Yūko walks towards the bushes, Masaya ambushes her, ties her up, and rapes her. He takes photos as he did with Manaka previously, before handing her over to his gang of henchmen, who detain her for him.

On the third day, Masaya follows Aoi to the subway and shows her a picture of her tied-up mother. Shocked, she can only follow his orders as he gropes her on a train. After getting off the train, she asks Masaya the reasons for his actions, at which point she recognises him as the same man she reported for molesting a woman earlier. Getting in a vehicle, Masaya and his henchmen take Aoi to a hotel owned by his family. He violently rapes her in a mini-suite room and again photographs her after withdrawing.

After this ordeal, Yūko and Manaka are taken into the room via a secret door. With all three captured, Masaya reveals his plans to make them his sex slaves. Yūko tries to cover for her daughters and pleads with him to take her instead. He considers this and tells Yūko he might spare her daughters if she can prove her worth. Yūko gives him fellatio while her daughters watch. When Masaya seems pleased at her performance, Yūko thinks she has won her daughters' freedom. However, Masaya reveals that he will never change his mind and that they are all there to stay. Yūko breaks down in the end, Manaka breaks next and finally Aoi as well. The main story ends with an ominous title card stating that as a new day starts, the Kiryū family horror has just begun.