is an adult bishōjo game

Bishojo game

A , or , is "a type of Japanese video game centered on interactions with attractive anime-style girls". These games are a sub-genre of dating sims targeted towards a male audience....

 released on December 4, 1998 in Japan by Aaru

Aaru

In ancient Egyptian mythology, the fields of Aaru or the Egyptian reed fields, are the heavenly paradise, where Osiris ruled after he became part of the Egyptian pantheon and displaced Anubis in the Ogdoad tradition...

. The title is exactly pronounced Ko Ko Ro. Kokoro means "heart" in Japanese, and the title represents the word "heart" being broken. The game deals with incest

Incest

Incest is sexual intercourse between close relatives that is usually illegal in the jurisdiction where it takes place and/or is conventionally considered a taboo. The term may apply to sexual activities between: individuals of close "blood relationship"; members of the same household; step...

, sexual abuse

Sexual abuse

Sexual abuse, also referred to as molestation, is the forcing of undesired sexual behavior by one person upon another. When that force is immediate, of short duration, or infrequent, it is called sexual assault. The offender is referred to as a sexual abuser or molester...

, homosexuality

Homosexuality

Homosexuality is romantic or sexual attraction or behavior between members of the same sex or gender. As a sexual orientation, homosexuality refers to "an enduring pattern of or disposition to experience sexual, affectional, or romantic attractions" primarily or exclusively to people of the same...

 and murder

Murder

Murder is the unlawful killing, with malice aforethought, of another human being, and generally this state of mind distinguishes murder from other forms of unlawful homicide...

.

The game was once banned of sales and was later re-released without consent of the Ethics Organization of Computer Software (EOCS) on January 29, 1999, changing a part of the story. The characters' relationships were changed from blood relatives to the family-in-law. During this period, the game brought record prices in the secondhand market. A novel adapted by Kakeru Sawano was published in June 1999.

The first part and the latter part of the game's original video animation

Original video animation

, abbreviated as media , are animated films and series made specially for release in home-video formats. The term originated in relation to Japanese animation...

 (OVA) adaptation were released by Alice Japan

Alice Japan

was established on April 4, 1986 as the adult video label for Japan Home Video .-Company information:The early AVs produced by JHV went under the Penguin label, the first title being the 30 minute long softcore Asobinasareya, Tadakurue starring Hidemi Nakajima released May 21, 1984 with...

 on December 21, 2001 and on June 21, 2002 respectively.

There are two sequel

Sequel

A sequel is a narrative, documental, or other work of literature, film, theatre, or music that continues the story of or expands upon issues presented in some previous work...

s to the game. The second volume Kokoro II, drawn by Yuna Kagesaki

Yuna Kagesaki

is a manga artist, born on March 3, 1973, best known for being the author of the manga Chibi Vampire. Her work has been published under four different names: , , when drawing...

, was released on August 25, 2000. The final volume Kokoro 0 was released on May 28, 2004. In the 2006 summer comiket

Comiket

, otherwise known as the , is the world's largest self-published comic book fair, held twice a year in Tokyo, Japan. The first Comiket was held on December 21, 1975, with only about 32 participating circles and an estimated 600 attendees. Attendance has since swelled to over a half million people....

, Yuna Kagesaki sold a manga

Manga

Manga is the Japanese word for "comics" and consists of comics and print cartoons . In the West, the term "manga" has been appropriated to refer specifically to comics created in Japan, or by Japanese authors, in the Japanese language and conforming to the style developed in Japan in the late 19th...

 that dealt with the game Kokoro II.

Story

A boy was raped by his father and mother. He had sexual intercourse with two sisters. One sister killed her father and mother. He murdered her and subdivided her body with an ax. He still engages in sexual acts, but the repressed memory

Repressed memory

Repressed memory is a hypothetical concept used to describe a significant memory, usually of a traumatic nature, that has become unavailable for recall; also called motivated forgetting in which a subject blocks out painful or traumatic times in one's life...

gives him pain.

Characters

He is an original hero. He had sex with his family. He murdered his sister. He doesn't enjoy sex. After he marries Mizuki, he becomes kindhearted. He becomes the president of the family business.

She is Soji's younger sister. She helps him to dismember their sister Kasumi. She changes her name to Asuka Yūki later. She becomes the vice-president of the company.

She is Soji's older sister. She murders her parents and is subsequently murdered by her brother. In one of the ending of Kokoro 0, the prequel, is revealed she was in fact her to give birth to Soji.

Soji's mother - Her maiden name is Ruri Yūki.

Soji's father. He was the president of a company.

She is senior of Soji. She becomes an office worker and she doesn't marry. She trains Subaru Kuonji.

He is Makoto's brother. He loves Soji and his sister.

She loves Soji.

Christine Russell

She is an overseas student.

She is Soji's teacher. In the sequel, she married Soji.

He is the son of Soji and Mizuki.

She is Asuka's daughter. Her father is unknown.

Kasumi transmigrates her.