The story starts with Tatsumi, a young man, returning to his home, where he is greeted by the merman Wakasa, who lives in his bathtub. The latter is given a bath mix, which would make it possible to turn the bath water pink, something the merman has always dreamed of. Meanwhile, Tatsumi reminisces about their first meeting and how he had taken him to his home, after he found the powerless merman stranded next to a river, although he only came to realize that he was a merman some time afterwards. Wakasa then starts to talk about his life around the upstream dam, which had recently gotten a little difficult. As he says how impudent humans are, Tatsumi silently thinks about all the impudent requests Wakasa already asked of him during his time living there. Following, Tasumi states that he would like to take a bath as well soon, but as he tries to switch places with Wakasa, the other starts complaining as he would dry out without water, resulting in the two of them taking a bath together. During their bath, Tatsumi asks Wakasa when he plans to leave again, to which the merman responds that he would prefer to stay because the river water was filthy. Being the nice person he is, Tatsumi gives in and lets him stay at his place.