Irina, now going by I.R., finds the Demon of Lust's sword and takes the Haru Netsuma as her medium.?
Gumina attempts to break off the engagment with Sateriasis, only to learn that he was planning to assassinate Cherubim, believing that Gumina had fallen for him.
December: Cherubim learns of Gumina's engagment to Sateriasis, and approaches her at a party. In an attempt to protect him from Sateriasis, Gumina harshly rejects him.?
In a fit of rage, Cherubim slaughters the entire household the next day.?
Before he can kill himself with shame, Cherubim is approached by I.R., who intended to have Ilotte contract with the Demon of Lust.?
I.R. instead offers the sword to Cherubim, and he contracts with the demon by stabbing himself in the chest.?
Sateriasis accidentally wipes his own memory while attempting to wipe the memories of a sole witness to his crime.?
Sateriasis believes himself to be his brother and becomes the new Duke of Asmodean. He secludes himself due to his lustful urges.?
January: Sateriasis wanders into Lasaland during the New Year's Festival and collapses due to his lack of sexual contact.
Sateriasis is rescued by Lukana, and he hires her to make him a new wardrobe, having her stay at the mansion while fighting his lustful urge.
Lukana rejects Sateriasis' love while returning her home, triggering his memory of Gumina's rejection, the massacre, and his deal with I.R.
Sateriasis chases after Lukana and brainwashes her,12 only to have his demonic form be spotted by Mikulia. He attempts to brainwash her as well, but is unable to due to the Demon of Sloth.
Sateriasis moves Lukana down to the basement and begins continually having sex with Lukana (and later other women in his harem) to control his lustful urges.12
February: I.R. tracks Mikulia down and she joins his harem voluntarily as she sees him as her "demon prince".12
Sateriasis wipes the people's memories of his interactions with Lukana and Mikulia.
Sateriasis brainwashes Lolan Eve and Mirigan Adi and adds them to his harem.12
Gumina and her father Classke visit and discuss the disappearances of women around Asmodean, and arrange to have a date between the two bethrothed to help recover more of Sateriasis' memories.
March: Sateriasis goes on his date with Gumina and learns about "his" older brother. Determining that Gumina had fallen for Cherubim instead of him and that caused his massacre.
Angered, Sateriasis goes on another massacre, this time at the Glassred Mansion. He then brainwashed both Carol and Gumina and added them to his harem.12
Sateriasis adds Hakua Netsuma, the older sister of I.R.'s medium, to his harem.12
Yufina gives a Marlon family heirloom, a golden key pendant, to her favorite retainer and her secret partner, Karchess Crim, before leaving for the Beelzenian Empire.
Sateriasis massacres Yufina's entourage and abducts her into his harem.12
Karchess begins investigating the disappearances.
Sateriasis adds Sonika Sonic, Lazuli Blue, and Priema Soap to his harem.12
April: Sateriasis and I.R. search for a vessel of sin that turns out to be a false lead and he meets Lilien.
Sateriasis woos Lilien and forcefully adds her to his harem after she resists upon realizing he abducted her friend Lukana.12
Rajih, Lilien and Lukana's childhood friend, confronts Sateriasis over his abduction. In response, Sateriasis heavily wounds him and he collapses. Rajih later claims that the Duke is responsible for the abductions, but is branded as a lunatic.
Sateriasis adds Mewtant Lusha, Tette Cetera, and Rio Neja to his harem.12
Sateraisis seduces and uses the spy Neruneru Nerune to abduct Maylis.12
I.R. gains an interest in Lukana due to her purple dream ability, but Sateriasis refuses to let I.R. use her.
Rajih is approached by Karchess to learn information about Venomania.
Lolan dies one morning after Sateriasis spends time with her, leading him to enchant the elderly ex-doctor Annlee Sweets to monitor the women's health.12 Annlee then discovers that Lukana, Maylis, and Mikulia have all been impregnated by the duke.
I.R. gives Mikulia a Clockworker's Doll she's been working on, and the Demon of Sloth migrates from Mikulia to the doll.
Karchess meets up with Elluka and learns from her that the pendant is a vessel of sin, and agrees to hand it over after defeating Venomania. The two make a plan to approach the duke later.
Elluka visits the mansion, and soon after I.R. attempts to flee with the sword and Lukana. Sateriasis confronts her, however, and she leaves Lukana at the mansion.
Karchess deviates from the plan and forms a contract with the demon of wrath and learns to transform the key into a knife.
Karchess visits the mansion disguised as Elluka, and pretends to be wooed by Sateriasis' magic.12
While dancing with his new bride in the basement, Sateriasis is suddenly stabbed in the chest by the golden knife. Sateriasis collapses as Karchess triumphantly reveals himself.12
As Karchess searches for Yufina, the rest of the women, freed from the hypnosis, flee the mansion.12
The lust magic leaves his body as Sateriasis' face returns to it's natural deformed state. He recalls that his lost memories, and realizes he never confessed his feelings to Gumina. He is unable to speak and watches her leave breathlessly.12