Jo (right) protecting Riu (left)
For centuries, merfolk have lived in the depths of the ocean—4,000 meters below the surface—where humanity cannot find them. One mermaid, Jo, finds herself caught up in the world of humans when her best friend Riu is arrested for having an affair with a human man, and has to save her from punishment.
A Sinner of the Deep Sea (Japanese:アビスアジュールの罪人; Abyss Azure no Zainin; literally meaning Sinner of the Azure Abyss) is a Seinen fantasy series by Akihito Tomi, creator of Manga such as Stravaganza - Isai no Hime. The series began in serialization in Enterbrain's Harta magazine in 2020 and ran for three volumes before its final chapter in February 2023.
On January 4th, 2024, Yen Press announced that they would be localizing the series in English.
Tropes:
- Become a Real Boy: Jo discovers there are highly rare pills that allow merfolk to become human upon ingesting. The effect is seemingly permanent unless they take a second pill that switches them back to their original form. Riu was hiding such a pill so that she could move onto land to be with Yuki.
- Cuteness Proximity: Jo can't help but be charmed by a whale calf that keeps nudging her into playing, eventually giving in after trying to brush it off.
- Forbidden Love: Both Riu and Yuki have been attempting to keep their relationship a secret from everyone. Once it does get out on Riu's side, she's arrested and imprisoned in a tiny cage with only Jo willing to pay her visits due to the huge stigma around interacting with humans.
- Interspecies Romance: Riu, a mermaid, is revealed to have been having an affair with Yuki,a human.
- Our Mermaids Are Different: The merfolk of this world live in a secluded society deep, deep in the sea. They resemble your classic half-and-half merfolk, human on top and fish on bottom, and can breath both water and air, having gills along their hips that connect to their lungs. They also have a form of bioluminescence, able to make their hair glow, to see in dark places. Being underwater at such depths also makes them very strong.
