Sateriasis Venomania

Duke Sateriajis Venomania is a powerful lord from the country known as Asmodean and the one behind the Venomania Event, where he abducted countless women from his country and its neighboring ones to drag them into his harem. He rapidly degraded himself committing numerous sexual perversions to the victims who fell in his grasp.

History
In his childhood, he had been mocked by others due to his physical appearance. This, along with the fact he was humiliated by his childhood friend Gumina Glassred, drove him to make a deal with Irina Clockworker. In exchange for his soul, he was given the Venom Sword, which gave him an incredible charisma that made him irresistible to women. With this new power, he began finding beautiful women and bringing them to his mansion, in which he began to build a harem by keeping the women in his basement.

Unfortunately, people noticed that women from all around Asmodean were beginning to simply vanish. A man named Kachess Crim, who had lost his love to the Duke, heard about where the women might have run off to. Disguising himself as a woman, Kachess Crim enters into the Duke's mansion, and, when confronted, stabs him with a poisoned knife. This, in turn, breaks the charm that the women were enchanted by, and Kachess frees them and flees.

Venomania, collapsing, looks up one last time to see Gumina, now a victim, and using his last breath begs her to stay because he truly loved her.

It's known that during the events of his harem, he made some women pregnant. It's known that Lukana Octo had a child of his, and this lineage continues into the late 900's with Gammon Octo. It's also implied he got Mikulia Greonio, also a victim, pregnant.

Skills
After stab himself with the Venom Sword, and sealing the contract with Irina and the Demon of the Lust, he gained access to the power of the Sword. The Vessel's powers allows him to charm any women just with a gaze, and acceding to its full power he is capable to literally transform in a goat-like Demon.

The Lunacy of Duke Venomania (EC 136)
The Lunacy of Duke Venomania explains his past life wherein he had been mocked and taunted by others. But soon, he made a deal with the devil to have an irresistible charisma to women. As a result, women are now flocking to his mansion's basement to create a harem for him. By some time, a jealous man, Kachess Crim, who had lost his love to Venomania, came to his palace, disguised as a woman, and stabbed him in the chest with a poisoned knife. The charm now broken, the women flee from his mansion, and as Venomania dies, he sees a glimpse of his childhood friend, and reveals that he had truly loved her.

Heartbeat Clocktower (EC 990)
Sateriajis gets a brief cameo in Heartbeat Clocktower during the "Lu Li La" chorus. Although only a quick flash by, he is labeled as the representative of Luxuria (Lust), before his former debut in The Lunacy of Duke Venomania.

Connections to Other Characters
Irina Clockworker: The "devil" who Venomania made a deal with. She gave him the Venom Sword, which he used to stab himself with, giving him his powers.

Gumina Glassred: Venomania's childhood friend-turned-bully. She falls under his spell and into his harem and is the last woman to leave the mansion, although she doesn't spare him more than a glance. Despite all this, he still confesses that he loves her as he dies on the floor.

Lukana Octo: One of the women in his harem. She became pregnant as a result of this.

Mikulia Greonio: One of the women in his harem. There is a possibility that he is the father of her son.

Kachess Crim: A man who snuck into his harem, disguised as a girl. He stabs Venomania, breaking the spell and freeing all of his victims.

Gast Venom: A descendant of Venomania who leads a mercenary group called the Asmodean Company.

Gammon Octo: He is a distant descendant of Lukana and Venomania; the fact that Gammon shares blood with the latter is the reason he is cursed.

Conceptualization and Origin
Duke Sateriajis' name comes from two terms for hypersexuality. His first name comes from the term Satyriasis, which means "a morbid or excessive desire for women". The term Satyriasis comes from Satyr,  hedonist creatures that features goat-like traits. This ties with the Duke's demon form.

Meanwhile, his last name is a combination of the words Venom and Nymphomania, which means "an excessive desire for men"; tying to what happened to the women he enchanted. The last name also could be interpreted as "Venomous Obssesion".