Nummer 5 in Kimihitos Fabelwesendamen-Sammlung ist eine sexy Nixe namens Melu. Die neue Rivalin ist für Mia Grund für heißblütige Eifersuchtsattacken.
A construction crew from the Interspecies Exchange Security Squad arrives while the girls are making a plan to hide Suu from Smith. The girls leave with Suu until the construction is over, only to realize that they have left Kimihito behind. They are forced to hide when pursued by security forces. All three of the girls somehow get wet, causing them to be assaulted by a dehydrated Suu. Meanwhile, Kimihito is searching for them. He is hit by a girl in a runaway wheelchair, who introduces herself as Mero. When they arrive at the park, Mero is almost assaulted by Suu, but Kimihito catches her in a plastic bag. Arriving home, they thank Smith for building a room for Suu; she reveals, however, that the room is not for Suu, but for Mero, who is revealed to be a mermaid. Miia becomes jealous when her accidentally breaking Mero's wheelchair results in Kimihito having to carry the mermaid around the house. She attempts to enlist Centorea and Papi's help in foiling the mermaid. When Kimihito knocks Mero into the pool to save her from a once-again dehydrated Suu, Miia thinks he is making a romantic advance and dives in after them, almost drowning when the cold water makes her sluggish. Later, as Miia and Mero take a bath together, the mermaid reveals that she has no intention of attempting to woo Kimihito away from Miia; all mermaids want to experience a tragic love similar to "The Little Mermaid". Centorea and Papi overhear this and believe that the two are plotting against them.
Même s'il est déjà difficile de s'occuper de Sû, Kimihito va devoir aussi accueillir chez lui une sirène.
La riunione strategica per decidere come proteggere Suu è interrotta dall'arrivo della Sicurezza negli Scambi Inter-specie. Credendo che siano lì per arrestare Suu, le ragazze scappano portandosela dietro. Kimihito parte al loro inseguimento, e si imbatte in una ragazza dall'aspetto nobile su una sedia a rotelle.
スーを守るためモン娘たちは作戦会議を開いていた。そこへ突如現れた他種族間交流法保安局。スーを捕まえに来たに違いないと焦った一同は、スーを守るため、公人を置いて外に逃げ出してしまう。慌ててモン娘たちを追いかけた公人は、そこで高貴な佇まいをした車椅子の女の子と出会う。 新たなホームステイメンバーはマーメイド族のメロ。公人は車椅子が壊れて不自由するメロにかかりきりな様子♡ 公人争奪戦のライバルが増え、ジェラシーに燃えるミーアは、あらゆる手段で公人の気を引こうとするが空回りばかり。一方、メロはみんなに公人に恋人がいるのか探りを入れていた。
슬라임의 존재를 들켜버린 몬스터 일행. 그러나 쿠루스의 집에는 수조를 만들어 준다는 업자들이 들어오는데…?
Meroune Lorelei, una elegante y hermosa sirena, se muda a la casa de Kurusu sin previo aviso. Aunque Meroune aclara desde el comienzo que no tiene ningún interés en casarse con Kurusu, Miia, la lamia, quien la considera una auténtica rival, está empeñada en demostrar lo contrario.
