animal characteristics

Do Geon, who had dreamed of musical success, ends up moving into a shabby rooftop room instead. While trying to shake off his gloomy mood, he goes into the bathroom—and in the toilet, he finds a goldfish.
“Huh?!”
Thus begins his life living together with an “Oranda” goldfish, which seems to go smoothly at first. But one night, Do Geon wakes up to a damp feeling on his back… and in front of him is someone flailing two legs.
“Human… something’s wrong with me.”