Merman in My Tub Vol. 2 (manga)
Mellow and responsible Tatsumi has gotten pretty used to his new roommate–the energetic and needy merman, Wakasu–who has taken what seems like permanent refuge in his bathtub. While regular visits from Wakasu's undersea friends and Tatsmi's affectionate little sister have become commonplace, the bathtub suddenly seems a little less safe when a sharp appears. Is their hungry new acquaintance friend or foe? Whether it's testing new bubble bath, hosting a butler cafe, or training for the Olympics, it's never a dull day in Tatsumi's bathroom.