It was another normal day inside the Yasaka household…as if. With Nyaruko, Kuuko, and Hasuta having fun inside his room, there never seems to be one day of peace inside his house, let alone his room. Yet, Mahiro still remembers the time he and Nyaruko kissed each other that day. Every time he comes near her face, he remembers that incident, which makes him blush. Of course, he would deny those feelings every time it was suggested, but Nyaruko, Kuuko, and Hasuta would try to intervene in some way. This would all change when someone rings the doorbell.
The person from the other side turns out to be child named Ghutatan with her butler, a round green bat named Roy Fogger. Here, Roy would state that they were invited to his place by his mother. On a Notebook, his mother informs them that she found her during her trip and seemed to be lost; therefore, she should stay at their place until they find out where she originally came from or where her supposed destination was. Until then, they are to babysit here, but how exactly should one take care of an alien child? After texting her defense corps about the situation, Nyaruko would easily take the task, providing her with everything she needs to know about in this world, from high school knowledge to nudity, of which Mahiro makes sure she does not do. Of course, this was all for the sake of getting the approval of his mother to be with him forever, of which both Kuuko and Hasuta take up the task, much to his dismay. Meanwhile, the text that Nyaruko sent to the planetary defense was unable to be sent.
Nyaruko would go all out to let her play a platinum-edition eroge, of which Mahiro quickly takes away from her. Kuuko would then ask if she was hungry, of which she tells Mahiro to make anything that is filled with his love, which, of course, were her own words. Hasuta would try to help out with cooking breakfast, but noise was coming from the refrigerator. Several large bugs would come out of the refrigerator and flew around the house, creating a mess inside the house. Kuuko and Hasuta would try to help, but their powers would only make things worse. Eventually, Nyaruko would take them away, but this was the last straw for Mahiro as he kicks the three out of the house. Little do anyone know that there were monsters lurking near his house.
Mahiro would return only to see that Ghutatan was in a complete mess as well. Mahiro sends her to the bathroom to clean herself up while he cleans the living room and kitchen. However, living a very sheltered life and a standard princess fashion, Ghutatan does not know how a bathroom works as her maids do everything for her. Mahiro has no choice but to help her with taking a bath as well as washing her hair. Afterwards, Mahiro would make her something to eat, but the maids apparently would feed her as well. She does indeed live the stereotypical rich life. Having no other choice, Mahiro would feed her as well. Finally, Ghutatan would sleep on his lap after a very exciting day.
This was the type of day that he was longing for ever since Nyaruko entered his life. It was a kind of peaceful day where it was only him and a younger sister alone and quiet together. However, even this peace would come to a halt as Nyaruko, Kuuko, and Hasuta enter from the window, jealous of the situation Ghutatan was in, with Kuuko still hungry for food. Nyaruko was even able to deduct that the two took a bath together. Immediately, the three wanted Mahiro to do something for them. Afraid of their menacing looks, Mahiro, carrying Ghutatan, and Roy run away as the three began to chase after him. Mahiro would ask Takehiko, Tamao, and Luhy about hiding Ghutatan or telling them not to tell Nyaruko, Kuuko, or Hasuta where he went, but they managed to catch up with him before he was able to finish his statement.
This chase would go all the way until Mahiro bumps into two odd but dangerously-looking alien lifeforms. Nyaruko, Kuuko, and Hasuta arrive to take care of them just in time before they harmed Mahiro. Nyaruko would quickly take out one of them while Kuuko and Hasuta would defeat the other. The explosion from their attack would knock Mahiro back as well as leave Ghutatan hurt. Nyaruko would try to say sorry to him, but Mahiro claims that this was the result of them having too much fun and not taking care of one’s surroundings. Mahiro would go home alone with Ghutatan, telling the three of them to do their job.
Mahiro would get Ghutatan patched up before making dinner for five, expecting Nyaruko, Kuuko, and Hasuta to come at any minute, of which they did not. Ghutatan asked if he was alright, of which he prefers this kind of atmosphere the most. Roy informs him that they are late, but Mahiro assures him that everything will be alright in the end.
The next day?, Mahiro would wake up for school, only to find out that the clock states that it was Sunday, which should have been yesterday. Mahiro tries to wake Ghutatan up, but she was not there. Mahiro would then search for Nyaruko, Kuuko, and Hasuta, but neither of the three were here as well. Where did everyone go?