A giant octopus-shaped sea monster in the eastern seas. The structure forming the mouth of this creature is a bare upper female torso. It exposes its mouth above the water's surface to lure passing ships, enticing them into its trap. Humans are just small snacks for the Cyrene, which feeds primarily on other fish and monsters in the sea. Seducing humans and killing them is just a part of the "mother" instinct in Cyrene's body.

Cyrene was a woman named Vivian when she was still alive as a human. During the journey back home on a cruise, she faced a maritime disaster with her 2-year-old child. As they plunged into the water, she tightly embraced her child, pressing him against her abdomen as if by doing so, she could return her beloved child to the womb. 

"If only he hadn't been born yet, if only he were still in my little room, he wouldn't have suffered such despair and pain." With this thought she died as a human being.

The Outer Ones heard her wish, and they fulfilled it. The giant sea monster born from the bottom of the ocean no longer fears the waters that killed her, but out of a protective instinct, it traps humanoid creatures and stuffs them into its sharp beak—the place that was once a womb.