On her 16th birthday, Himari Momochi receives a letter stating she has inherited a mansion called the "Momochi House." Having been raised in an orphanage, this mansion is the only thing left of her real family, so Himari pays no mind to the rumors that it may be haunted. Upon entering it, she meets Aoi Nanamori and his companions, Ise and Yukari, who all seem to be squatting in her new home. Although they warn her to leave the house, Himari vows to be the one to make them leave instead. But soon, she is attacked by youkai and finds out that the house sits in the space between the world of the living and the spirit realm. Even more surprising, Aoi was chosen to be the guardian of the house—a position originally meant for Himari. But this great power came with an awful price: Aoi can never leave the mansion, and his existence in the human world has been erased. Ignoring his pleas for her to leave the mansion, Himari promises to help Aoi break the housebound curse as she begins living under the same roof as him.

Akane Nishimura's quiet nature makes her classmates perceive her as a gloomy and unlikeable person. Combined with her intimidating gaze, it earns Akane the ominous nickname "Grim Reaper," condemning her to endless bullying for her supposed cursed powers that bring misfortune to everyone around her. However, none of these rumors deter transfer student Taiyou Takada from trying to befriend Akane. As someone who finds the supernatural fascinating, Taiyou approaches the Grim Reaper without hesitation, blissfully unaware of the complicated situation within the class. His bright personality and optimistic worldview may just bring about the change that Akane desperately needs.

The player Dongdong mistakenly entered the game world "Azure" and changed into the skeleton, the weakest wild creature. The unidentified Dongdong used his years of gaming experience to amass a band of wild monsters early on. He met the main character Bubble, made a deal with her to become her strongest pet, and then set off on an amusing and thrilling adventure with Bubble and his new pals in "Azure." The phenomenon of NPCs and wild monsters in the game gradually awakening and yearning for the human world was also identified at this time by Dongdong. To learn the truth and get back to your regular life. The main character group, lead by Dongdong, as well as awakened NPCs, regular players, game developers, and other entities started to debate how the two worlds were connected.