A species of mermaid with the characteristics of a shark. Rarely seen in the generally gentle Mermaid family, they appear as being extremely ferocious. They can easily sense the presence of humans, and can identify the precise location of a man hiding inside a ship. Because this sense is so keen, by recognizing the presence of a man, she reacts almost excessively strongly, and becomes highly aroused. If they find a man who fell into the sea, they will sink their teeth into him as if mercilessly devouring his body as they ravish him. Even though they don't actually eat people, due to how they appear when attacking men, they've gained a reputation as "man-eating sharks".

Habitat: Sea Disposition: Ferocious, Arrogant, Cowardly Diet: Carnivorous, prefers seafood

They have sharp fangs and strong jaws, being able to bite even iron chain to shreds, and bite holes through the bottom of a ship. On the other hand, their teeth have the same properties as demon silver, so they don't cause harm to humans. Those who are bitten spill out their spirit energy instead of blood, and it will mingle with the Mershark's own demonic energy and dye the sea red. When biting, the Mershark will rip out the man's spirit energy instead of his flesh, and at the moment of being bitten, the man's body is hit by a severe tingling that's enough to almost knock you unconscious, and the spot will continue to throb and heat up, and the man will be unable to resist underwater and cannot escape their sexual assault. They embrace the man tightly and intertwine their bodies, preferring to have intercourse as closely as possible, making the man penetrate them more deeply, and roughly violating him as if they were devouring his male organ. In addition, their rough "sharkskin" scales have the same properties as their fangs, and as they grind up against the man during sex, they cause a similar heat and throbbing throughout his whole body. The man won't be able to keep himself from repeatedly ejaculating inside of them.

Even though they are very ferocious in this way, in truth, they are also somewhat timid, which becomes prominent once they get a husband. They will often bite their husband's body in the middle of sex, which is just their way of expressing that they don't want their husband to leave them, in which case you can reassure them by hugging them and stroking their head. Also, since they had rather different "weapons" in the era of the previous demon lord, with their entire body being a weapon to hurt humans, outside of sex they treat their husband with utmost care and gentleness like a fragile treasure, so they could be considered worriers, directing their ferocity against all that would cause their husband harm. Among the humans who fear the Mersharks, it is said that they are attracted by the smell of human blood. In truth, they actually are sensitive to the smell of human blood, and if a human is bleeding in the sea, they will swim towards them at full speed, even if they're far away. But this isn't them attacking the human, but rather fearing for their safety, and hurrying to help them. Sometimes they may appear before drowning men even faster than a "Sea Bishop".