Fairy's Island

Fairy’s Island (妖精の島 Yousei no shima) is a remote island located to west of the Safina region. As the name implies, it is home to a band of fairies and elves.

Description
After Luka hears from a Sabasa Guard about Sara being kidnapped for the second time, he rushes to Sabasa Castle to ask the Sabasa King about this. The king informs Luka that his daughter has been genuinely kidnapped this time, with a letter stating the conditions for her release involve the entire human population of Sabasa pulling up stakes and leaving for good - conditions which are naturally unacceptable. According to Alice’s sense of smell, the letter was sent by a queen-class elf and fairy. The King also has a lead to Fairy’s Island, and sends Luka out there by himself (as soldiers would simply get in the way and Alice once again refuses to take part).

Shortly after arriving, a Trick Fairy attacks. Shortly after, Luka meets the Queen Fairy and Queen Elf, who have indeed taken Sara hostage. They reveal Sabasa was originally their territory, but they were pushed further away from their homes as the generations passed. Being pacifists, they refused to fight, however enough is enough, and it’s time to strike back – not by holding the princess for ransom, but by turning her into a monster and then sending her to do the same to the rest of Sabasa’s nobility. Sara tries to reason with them, but to no avail.

Queen Fairy then distracts Luka while Queen Elf begins the ritual. The fairy becomes sealed, but Luka’s words of reason do not reach the elf.

Queen Elf shortly falls, but while they were fighting, the ritual continued. However, Sara suddenly gains extraordinary power that the elf mentions to be equal to a queen-class; her monster blood, inherited from Sphinx, has awoken.

Luka fights and defeats Sara’s succubus form. Afterwards, Queen Elf seems ready to listen, until she holds up a dagger to Sara’s neck. Suddenly, Granberia intervenes and attempts to execute the Queen Elf for possible rebellion against the Monster Lord, but is stopped by Sara, saying that the Monster Lord would disapprove of her subordinates killing each other. Queen Elf assures her allegiance to the Monster Lord and Granberia replies that she is working to alleviate their problems. Sara and Luka also agree to find a conclusion for the elves and fairies to coexist with humanity, and Queen Elf finally looks forward to it. Before she departs, she reports to Granberia about Black Alice, a character believed to be leading a rebellion against the Monster Lord. After Luka and Granberia exchange words about how far they’ve come, Granberia attempts to teleport, only for Sara to accidentally bump into her and be taken away.

In Chapter 3, after Luka and Alice arrive back at the Monster Lord's Castle, Queen Elf and Queen Fairy arrive as well, reporting about the movements of Ilias's forces in Fairy's Island and thus forcing them to evacuate. They say that humans captured during the assault were relocated to their island. Tamamo butts in, saying that there's something about a Drain Lab there according to Promestein's discs. A facility underground, built to drain men's semen for decades. Tamamo says the island is a sacred place and full of energy, that's why it's chosen to be a place to build a lab like that.