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1. Deep Waters by Ridaos

   Fandoms: 鬼滅の刃 | Demon Slayer: Kimetsu no Yaiba (Anime), 鬼滅の刃 | Demon Slayer: Kimetsu no Yaiba (Manga)  

   • Explicit
   • Graphic Depictions Of Violence
   • F/M, M/M
   • Work in Progress

   11 Jan 2026

   Tags

   • Graphic Depictions Of Violence
   • Shinazugawa Sanemi/Tomioka Giyuu
   • Kochou Kanae/Shinazugawa Sanemi
   • Iguro Obanai/Kanroji Mitsuri
   • Shinazugawa Genya/Tokitou Muichirou
   • Shinazugawa Sanemi
   • Shinazugawa Genya
   • Kochou Shinobu
   • Kochou Kanae
   • Kamado Tanjirou
   • Kamado Nezuko
   • Ubuyashiki Kagaya
   • Kanroji Mitsuri
   • Iguro Obanai
   • Kibutsuji Muzan
   • Tomioka Giyuu
   • Gyutaro (Kimetsu no Yaiba)
   • Daki | Ume (Kimetsu no Yaiba)
   • Rengoku Kyoujurou
   • Tokitou Muichirou
   • Akaza | Hakuji (Kimetsu no Yaiba)
   • Hantengu (Kimetsu no Yaiba)
   • Tsuyuri Kanao
   • Kokushibou | Tsugikuni Michikatsu
   • Gyokko (Kimetsu no Yaiba)
   • Alternate Universe - Modern Setting
   • Merman Tomioka Giyu
   • Trans Tomioka Giyuu
   • Tomioka Giyuu is Bad at Feelings
   • Sweet Kanroji Mitsuri
   • Mermaid Kanroji Mitsuri
   • Curses
   • Immortality
   • Shinazugawa Sanemi is Bad at Feelings
   • Top Shinazugawa Sanemi
   • Shinazugawa Sanemi Being an Asshole
   • Minor Iguro Obanai/Kanroji Mitsuri
   • Good Friend Kamado Tanjirou
   • Human Kamado Nezuko
   • Slow Burn
   • Self-Harm
   • Human Daki | Ume (Kimetsu no Yaiba)
   • Human Gyutaro (Kimetsu no Yaiba)
   • Eventual Smut
   • Eventual Romance
   • Possessive Behavior
   • Trans Mpreg | Trans Male Pregnancy
   • Everyone is 18+ unless stated otherwise
   • Soft Tokitou Muichirou
   • Merman Tokitou Muichirou
   • Blood and Gore
   • Interspecies Relationship(s)
   • Interspecies Sex
   • Biting

   Summary

   Sanemi had one reason to join the Ubuyashiki Defense Force: hunt down the man that drove his mother to kill his siblings. After going undercover, Sanemi rescues a strange fish creature. The fish creature, Giyu Tomioka, becomes a part of the Ubuyashiki Defense Force, much to Sanemi's displeasure. Without knowing it, Sanemi and Giyu become intertwined. Both are learning about each other, and both are learning to unpack their deepest and darkest pains.

   Merman Giyu x Human Sanemi

   Language:

   English

   Words:

   46,818

   Chapters:

   16/?

   Comments:

   19

   Kudos:

   186

   Bookmarks:

   21

   Hits:

   3,654