Worried that the authorities will take Suu away, Miia, Centorea, and Papi take her outside and hide from them, but Kimihito did not follow them. Suu, dried out from being outside proceeds to molest the other three girls in an attempt to gain moisture. The government people who come by however don`t seem out to arrest someone, but seem to be construction people who make more alterations to the house. Kimihito goes out to find the girls and gets hit by a girl on a wheelchair heading down the slope named Mero, who saw where they had gone.
Mero, who turns out to be a mermaid, is yet another monster girl put under Kimihito`s care, and the construction work at the house, which added a deep pool, was for her benefit. Smith tells them that with so much work to do she can`t really be bothered to worry about Suu. The girls have varied reactions to their new housemate, with Papi nonplussed and Centorea impressed by her regal bearing, but Miia is jealous and behaves churlishly. Later, Miia dives into the new pool after Mero and Kimihito, nearly drowning, but after she is rescued she apologises for her rudeness and Mero explains how she has no plans to marry Kimihito but rather wishes for a tragic romance like the Little Mermaid`s.