Beelzebubs

Beelzebub are Fly Queens, and only three remain in existence. They were so powerful and uncontrollable that Alice the I (First), the founder of the Monster Lords, was forced to seal them within the Calamity Box. Captain Selene would eventually come across that box and accidentally release them, however she managed to contain them off before she met her demise.

Each Beelzebub has a colored carapace that matches their hair, along with pincered arms and an abdomen lined with breasts of varying sizes. Beelzebub A has a purple carapace and has six enormous breasts on her abdomen. The busty Beelzebub B has a red carapace and an abdomen with lots of large breasts while the petite Beelzebub C has a green carapace with an abdomen lined with smaller breasts.

Selena, a woman who claims to be Selene's granddaughter, requests Luka to close the box that was responsible for her grandmother's death 50 years ago, in return Luka receives the Purple Orb.

When they reach Selene's ship, they notice a barrier. According to Alice, the barrier is keeping something in.

Upon reaching the captain's room within the ship, Luka encounters the trio of Beelzebubs. Barely holding out but managing to seal one as the others radiate power, Alice steps in and assists Luka as it is the Monster Lord's role, and kills the other two.

Battle Overview
Beelzebubs are an extreme hassle; they tend to use their restraint attacks more often, due to this they can easily overpower Meditation. The best way to hold out is use Undine + Serene Demon Sword followed by Gnome + Sylph + Earth Rumbling Decapitation.

After Luka seals the Beelzebub A, power radiates from their bodies. Alice steps in and fights alongside Luka. The remaining Beelzebubs then direct their attacks to the Monster Lord, only to be obliterated by constant use of her powerful magic. Beelzebub B eventually dies, followed by Beelzebub C.

If Luka is defeated, he is mounted on A's abdomen for a vaginal intercourse as she lays eggs in his rear.

Trivia

 * Beelzebub A’s design seems to reference to an illustration in the Dictionairre Infernal by Jacques Auguste Simon Collin de Plancy. The depiction of the fly-based beast inside the book features skulls and crossbones on its wings.
 * Their stats refer to only one Beelzebub, meaning that all of them have 8,000 HP.