As Mahiro finds a curious handheld games console in a used game shop, he finds himself trapped in a cursed dating sim, where he is the protagonist and everyone else is in strange roles. In order to escape, he must attain a good ending with one of the others.

Another day, another attack from the mysterious Nightgaunt monsters, and another resounding victory for Nyarko and her Space CQC. Rather than waiting for the monsters to attack, Nyarko announces her plan to go on the offensive. In order to take out all their enemies at once, Nyarko and Mahiro head to the underground auction held at their enemies’ base, R’lyeh. However, the two find themselves face to face with an assassin, Nyarlathotep’s archnemesis, Cthuga the Living Flame.

To try to chase Kuune away, Mahiro and Kuuko keep acting like a couple, but Kuune still isn’t convinced after seeing their awkward date, adding that she can’t see the subtle lust for each other in each other’s eyes. After having to see Mahiro and Kuuko act like their are engaged to each other, Nyarko finally…

The deities of the Chutlhu mythos who live in ordinary high school student Yasaka Mahiro’s home — Nyarko the Nyarlathotepian, Kuuko the Cthughan, and Hasuta the Hasturian - are enjoying the wonders of Earth entertainment yet again. They drag Mahiro along as they indulge in video games, shopping, cosplay, and more…

One night, Yasaka Mahiro finds himself under attack from a mysterious monster. In his moment of need, a silver-haired, green-eyed girl appears. "I’m the chaos that always crawls up to you with a smile, Nyarlathotep." Identifying herself as the deity from the Cthulu Mythos, she claims to have come to protect Mahiro. However, she tricks Mahiro into leaving his home, goes shopping at anime shops, and in general mixes business with her personal affairs. Meanwhile, they are assaulted by another mysterious monster. Why do these monsters keep attacking Mahiro.

Mahiro’s parents return suddenly from their trip abroad, giving the two aliens no time to come up with an excuse for living in their home, and leaving Mahiro flustered. The moment Yoriko hears Nyarlathotep’s name, she flies into battle with a fork in each hand. Who knew Mahiro’s own mother was a deity hunter? What an unbelievable secret! Mahiro tries to calm down Yoriko, but in the commotion, Noriko discovers Shanta-kun…

The Celaeno Library in the Pleiades star cluster is home to the largest book collection in the universe. It’s said that even variants of Yiu-th only handed out at events can be found there. Mahiro is dragged along for some reason as Nyarko goes there to return a book. Hasuta, a former worker at the library, does his best to show Mahiro around, but they soon encounter two evil deities who have infiltrated the library…

Mahiro’s mom Yoriko is kidnapped by a mysterious woman for some unknown purpose. Kuko is also blackmailed into helping her. Mahiro, Nyaruko and Hasuta set out to R’lyeh again to rescue them. During the events, Mahiro and Hasuta have a series of awkward moments.

Someone has killed the gods of the Dreamlands, and their next target is Nyarko. Meanwhile, Nyarko moves into the Yasaka home and begins moving into Mahiro’s every day and school life. Mahiro’s anger continues to grow as Nyarko demands his affection. Kuko appears once again before the two when she transfers into their school. Having joined the Planetary Defense Organization, Kuko has been assigned to go to Earth to solve the Dreamlands murders with Nyarko.

Mahiro finds that his mother was kidnapped for her expertise with game consoles, however the situation ends up being more messed up than it seems. Afterwards, the gang goes to the beach and hot springs where Nyaruko makes another attempt to seduce Mahiro.