Due to a mass sacrificial summoning ritual, Eirene found herself summoned into the other world as the new owner of the dark and gloomy Demon King's castle. She was flabbergasted by the situation, but everyone died due to the ritual, leaving her all alone with many questions left unanswered.

When she arrived, her memories was cloudy, she can even hardly remember her name. However, she quickly realized that this situation was pretty satisfying as the castle have almost everything ready. It seemed like before sacrificing themselves, the army had prepared for her necessities.

She didn't get lonely, it was as if she was used to it, although unfortunately she couldn't remember the reason. She could also use magic for almost everything, which make her life much easier despite the sudden change of environment.

Adapting quickly inside the castle, her life went calmly and smoothly for six months, until the Blood Moon Festival, the time where the kingdoms gave offerings to the almighty Demon King.

Eirene tried to complete the procedure exactly as what she read in the castle's library and succeeded. If there were problems, it would be the offerings given. Between the seven kingdoms exist on the western continent, three gave her materialistic gifts.

While the other four gave her children sacrifices.