|Japanese Name:||人魚 (Ningyo)|
|Manga Debut:||Episode 324 (Manga)|
Merrow are a race of astral Mer-Folk that live in oceans, through they can exist in both the physical and Astral planes like the Elves. As in the case of Isma, merrow appear to have two names: a common name that they can be called by and an Astral name that would give the wrong person absolute control over them.
In battle they can use their voices to fight, with Isma's mother describing it as singing.
Isma told Isidro and Schierke a story about a group of merrow who waged war on the Sea God and after losing many of their kind, managed to seal it on an island to restrict its movements. The merrow eventually faded into legend, though Isma is revealed to be the child of a merrow woman and a fisherman on the island where the Sea God is imprisoned. But the villagers have long worshipped the Sea God so it would not take their fishermen while demonizing the merrow for sealing the creature on their island, resulting with Isma being ostracized by even her reluctant father who managed to express her love to her at the end of his life.
After the World Transformation enabled the Sea God to eventually break free from its confides, Isma learns that her mother and the merrow are alive as they make their presence known to help Guts's group defeat their age-old enemy. In gratitude for Guts's deed, the merrow aid the crew of the Sea Horse as their escort to the island of Skellig.
- "Merrow" is an Irish-Scottish term for "Merfolk", the kanji also making the word "Ningyo" (人魚) which also means "Human-Fish" and can refer to a "Mer-Person".