Merman in My Tub (2014)
Original title: オレん家のフロ事情
Merman in My Tub is a 2014 Japanese-language animation series. It stars Nobunaga Shimazaki, Yuuichirou Umehara and Yoshihisa Kawahara.
Tatsumi is a high school student who lives on his own, until a merman named Wakasa takes up residence in his bathtub. His solitary lifestyle is turned upside down by the self-centered (but handsome) new roommate.
Where to watch Merman in My Tub
Stream: Crunchyroll, Crunchyroll Amazon Channel