Keiichi Sumiseki

 is the main villain from the Illusion/Triangle/Delta-brand Japanese Visual Novel/Game, Shiiku Hakusho ~Kusari ni Tsunagareta Doukyuusei~.

Keiichi is the spoiled and entitled perverted son of a powerful and wealthy Japanese Businessman with strong political ties. Which means that Keiichi has the connections and pull to do and get whatever he wants. He does not even need to go to public school.

However, because Serina Aihara ("Sarina" in some translations), a beautiful schoolgirl caught his attention one day, he transferred to her high school with the determination, "She will be mine". And by that he meant to make her the sexual slave for his prized purebred Dalmatian, Leo. Although one of the game's four paths ends with Serina as Keiichi's pregnant bride, the most popular path as supported by cover art ends with her ""marriage" to Leo.

To the end of his nefarious purposes, Keiichi tricks Serina to his apartment to meet his dog Leo because she has a love of animals but her own apartments do not allow her to have any pets. Shortly after Leo mets her, Keiichi drugs Serina's papaya juice and she drifts off.

Upon waking, Serina found herself frog-tied and exposed with clothing askew.

Keiichi then proceeded to subject her to weeks of sex with animals, from dogs to pigs to horses, until her spirit was broken enough she could be returned to school yet still submitting to his commands. She unable to resist him or Leo, whom she grew to love, never blamed, and gave herself willing to.

Keiichi then set her on an escalating series of public sex encounters with Leo until he exposed her in the act on the school auditorium stage in front of her entire class.

One ending detailed the police questioning Keiichi about Serina's subsequent disappearance—she ran away after the school auditorium humiliation—but he smoothly talked his way out of further suspicion.

Another ending detailed Serina's runaway life, having sex with every random street mutt which wanted her.

The longest path also included Ms Aika Shinohara, Serina's homeroom teacher and a close family friend. In digging into the truth about Serina's alleged sudden "illness" and "quarantine" at a Sumiseki-influenced medical facility, she got insistent enough Keiichi felt it prudent to kidnap her as well, locking her away to be the sexual plaything for a group of adult chimpanzees. She too eventually broke and fully embraced that life to the point she was given the key to her cage but willingly went back in. Keiichi even set up a special truck with drop away sides to reveal a barred cage so Aika could put on public sex shows at a busy intersection of town—hinted to be Akihabara—with the chimpanzees, driving off before police could arrive.

During Serina and Leo's "wedding", Keiichi was approached by the main villain of another series of Delta Visual Novels, marking Shiiku Hakusho as in the same universe and a "spiritual sequel" to them. An influential figure in a world of powerful and perverted subculture, the gentleman assured Keiichi Sumiseki of a lucrative future "training" more girls like he did Serina.