Merman in My Tub is a Japanese comedy manga created by Itokichi, first serialized in Monthly Comic Gene from 2011 to 2020. The story centers on Tatsumi, a high school boy living alone, who saves the charming merman Wakasa and allows him to live in his bathtub. Their daily lives soon get crowded with a quirky cast of aquatic friends, leading to plenty of slapstick mishaps and hilarious household chaos. The manga was adapted into a short-form TV anime in 2014. A live-action adaptation was announced for Taiwan in 2022.
The story is set in modern-day Japan, mainly inside Tatsumi’s house and especially his bathroom.
Wakasa, a merman, brings along a handful of other mystical aquatic beings who adapt human forms with unique features.
Creatures like Takasu (octopus), Mikuni (jellyfish), and Maki (snail) bring their ocean personalities into land life, creating comical culture shock and blending fantasy with slice-of-life elements.
Tatsumi, a quiet and capable teenage boy, lives alone after using his late grandparents’ house for school.
One day, he saves an exhausted Wakasa from a polluted river, discovering that Wakasa is a dazzling, golden-haired merman.
Wakasa instantly settles into Tatsumi's bathtub, refusing to leave and disrupting Tatsumi’s single life.
Wakasa's friends soon join in: Takasu the handyman octopus, the gentle Mikuni the jellyfish, and the gloomy snail Maki.
They crowd the bathtub, bringing wild antics, odd jobs, and hilarious misunderstandings to Tatsumi’s peaceful home.
Even Tatsumi's little sister Kasumi gets involved, while the ever-present rubber Duck-chan observes the chaos.
- Merman: A male merfolk, the species Wakasa belongs to, with the upper body of a human and the tail of a fish.
- Rubber Duck (Duck-chan): A classic yellow bath toy that unexpectedly becomes a comedic narrator in the anime.
- Slice-of-life Comedy: The genre, focusing on humor drawn from everyday routines with a supernatural twist.
The manga developed a loyal fanbase for its unique setting—a modern boy sharing his bath with mythical guys.
Its blend of comedy, fantasy, and everyday teen problems set it apart from traditional mermaid tales.
The short anime series expanded its reach, making Wakasa and Tatsumi’s quirky friendship widely loved.
The anime’s opening theme is “Fatal Wound” by Matenrou Opera, giving the series an energetic and dramatic tone.
Merman in My Tub ran for 113 chapters across eight manga volumes published by Kadokawa/Media Factory.
The 2014 anime adaptation aired in 13 short episodes on BS11 and online platforms like Niconico and Bandai Channel.
A live-action adaptation is set for Taiwan, announced in Monthly Comic Gene.
The anime was produced by Asahi Production with direction by Sayo Aoi and series composition by Yuniko Ayana.
Koji Haneda served as character designer and chief animation director.
The project was brought together by the "Orefuro Production Committee."
The story’s author, Itokichi, debuted "Merman in My Tub" with the launch of Monthly Comic Gene.
The manga’s premise mixes domestic life, fantasy creatures and lighthearted humor born from the clash between aquatic and land personalities.
A special edition of Volume 6 included a drama CD.
The show features a unique, fun dynamic between human and mythical, making even mundane things like bathtime entertaining.
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