Well, I'm a wizard. This time, it's a seemingly innocent sister who has fallen into evil. There are depictions of a large number of jewel-like objects embedded in the body, so please be careful if you are not a fan.
Now, regarding this work... This is the story of Yuel, a serious evil believer who pretends to be a kind-hearted sister, and the hero who is used to resurrect the evil god through her schemes. Well, there are a lot of things to be said, like what a demon nucleus is and why it's sealed inside your body, so let me explain a bit.
In the first place, the demon core was a long-standing problem for people living in the kingdom because it was a fragment of the power of an evil god that had been torn apart by the god of light, and powerful monsters could be born from this core. Then a girl named Euel appears, who possesses the power to seal away the demon core. It is unclear how she acquired the technique of "using her own body to seal away the demon core." Perhaps it was an arcane art passed down in the Temple of Light, taught by an evil god, or perhaps it was invented by the king himself through research into ancient texts in order to save the kingdom from danger. No matter how many times you defeat him, he will eventually revive by scattering miasma all around him... For the kingdom, which was plagued by such troublesome monsters, the existence of Euel, who could seal the demon core, was a ship to cross. Therefore, he teamed up with the hero, who was extremely strong but lacked the power to seal away monsters, and had him perform demon extermination. However... it seems that Yuel's goal was not to seal away demons, but to collect the evil core, which is a fragment of an evil god, and use his own body as a catalyst to resurrect the evil god.
So... if all the fragments were gathered together, Euel's body would become an evil god, posing a threat not only to the kingdom but to all of humanity. At this point, I haven't described what happened to the original consciousness of the evil god, but... well, the basic purpose is the same, so I guess it's like, let's just let it do what Yuel likes for a while.
Well, it's like this, and there are some settings... but the basics are fineZ, "It's kind of erotic!" I would appreciate it if you could take a look at it with a vague understanding of the situation. As a magician.