The 12th Chapter of Monster Musume: Everyday Life with Monster Girls.
The story begins shortly after the events of Chapter 10, with Meroune Lorelei beginning to settle into the household. When Kurusu Kimihito begins to carry her up the stairs. Miia immediately misunderstands the situation as the two having a romantic moment and jumps on Kimihito's back, knocking all three of them to the floor. This results in Mero's wheelchair being destroyed by Miia's tail and Kimihito being forced to carry Mero around the entire day as Ms. Smith cannot bring a new chair until the next day. Miia is upset that her actions have caused Mero and Kimihito to spend time together. Centorea tries to calm Miia down, but the Lamia is convinced that Mero is her most serious rival, as she sees the other girls as having flaws that make them unsuitable as marriage candidates. Miia's concerns are only increased when Mero asks Kimihito if he has a girlfriend.
The question surprises Kimihito causing him to trip and accidently grope Mero's breast. Miia gets more upset at the sight, forcing Kimihito to panic and accidently pull off Mero's bikini top, only distressing the Lamia more. Mero explains that the situation is not entirely Kimihito's fault as Mermaid's are covered in a slime membrane so their gills do not dry out and that she does not mind if Kimihito sees her naked. Miia believes that Mero is already charmed by Kimihito and decides that she must start trying new ways to seduce him immediately. Seeing Mero is covered in slime, Miia plays with Suu in order to cover herself in the Slime and make her appear wet. When she suggestively presents herself to Kimihito, the romantic subtext is lost on him and he suggests that Miia takes a bath.
With her first plan foiled, Miia decides to lower the temperature by messing with the Kurusu House's heating system, figuring the Mermiad will freeze becausing she is in effect only wearing a bathing suit. This ultimately backfires as Miia's cold blooded reptile physiology causes her metabolism to slow down, forcing her into hibernation, while Mero remains comfortable as Mermaids are acclimated to the freezing depths of the ocean. Kimihito notices the change in temperature and tries to raise it but finds the batteries in the remote control are dead and he leaves to find new ones.
Seeing that all of her plans are failing, Miia makes the decision to enlist the others girls' help while Kimihito is out of the room. Papi immediately abandones the idea as she forgets it and would much rather play wih Mero. Centorea, on the oher hand, is more proactive and begins questioning Mero on who she really is as Mero speaks in a very formal dialect and everyone, including the usually careless Smith, treats her with very high reverence. Instead of answering the question Mero asks Centorea is she Kimihito's girlfriend, throwing the Centaur off guard. Mero continues by saying that she is impressed by Centorea's loyalty to Kimihito and praising her knight like behavior. This causes Centorea to feel like she is standing in front of royalty and she is forced to bow to the Mermaid. Miia, finally tired of losing tells Mero that she has no intent on letting the Mermaid be with Kimihito, to which Mero ominously replies that the feeling is mutual. With her gills dried out from the dry air, Mero asks a now returned Kimihito to bring her to her room.
Miia becoms more upset and reveals to Centorea and Papi that she wants Kimihito to herself is because when she was a child she liked to read fairy tales that ended with a prince and princess living happily ever after, and that she always wanted to be Bridal Carried like a princess since she was little, with Cerea thinking to herself that it's biologically impossible for Miia to be carried that way. A frusated Miia then says she does not like that Mero is able to tempt Kimihito in a swimsuit, to with Centorea tells her to just wear a swimsuit herself.
In her room Mero asks Kimihito again if he has a girlfriend. But before he can answer Miia and Papi enter the room in their swimsuits. Miia tries seducing Kimihito as she is confident that she is showing more skin than Mero, but is interrupted by Centorea who enters the room in an even more revealing swimsuit. Miia questions why Centorea is trying to seduce Kimihito only for the Centauride to reveal that the suit is too small because she borrowed it from Miia. Centorea is then forced to leave when Papi climbs under her pareo and inadvertently stimulates her dragging Papi along.
As Miia turns her attention back to Mero and Kimihito she is horrified to see the Mermaid pulling Kimihito into the pool. Miia jumps into the pool in an attempt to save Kimihito, but as she dives deeper towards the two she finds that she is unable to move. Because her body temperature was lowered from earlier her body starts to shut down and Miia begins to drown at the bottom of the pool. Kimihito then appears and brings Miia back to the surface with Mero's help. When they surface Mero is greatly concerned and tries her best to warm Miia while Kimihito's head is engulfed by Suu.
Mero reveals Kimihito pushed them into the pool as Suu tried attacking them because she was dehydrated from when Miia changed the house's temperaure earlier. Realizing her mistake, Miia begins to feel bad about how she has treated Mero and goes to take a bath to raise her body temperature. Mero decides to join her.
In the bath Miia apologizes to Mero for being rude, but still reaffirms that she will not let anyone else be Kimihito's wife. Mero reveals she is fine with that as she wants a "tragic romance" like the Little Mermaid and she wants to be Kimihito's mistress, not his wife. Mero starts molesting Miia and says she will help her become Kimihito's wife as long as she does not mind Mero being his mistress, a situation that Miia does not like the sound of. Outside of the bathroom the other girls listen and Kimihito is glad that everyone is finally getting along.
- Meroune's desires and feelings for Kimihito are revealed
- More information about Mermaid biology is revealed.