In some ways, the natural born magician Patchouli Knowledge is like a typical human. In other ways, she is not human at all. She never needed to do what a human typically needed to do to survive, namely eating and sleeping. Though she sometimes engages in such activities, she does not receive any of the benefits that a human would reap from them. As a result, her physical body is extremely weak. She gets around using levitation, all of her movement relying on magic. But no amount of magic can activate the drive that is innate in all other living beings. No matter how hard she tries, Patchouli cannot experience sexual pleasure.
The collection of books in the Scarlet Devil Mansion covers all manner of things, and sex is no exception. However, though she has read everything there is to read about virtually every sexual topic known to exist, she cannot put any of the theories she has formulated to practice. She tried masturbating and felt nothing. She tried listening to other residents of the mansion as they discussed their sex lives and felt nothing. No matter what, Patchouli could not and cannot feel anything sexual.
Her eyes point themselves to a mysterious pamphlet that appears as Patchouli absentmindedly turns a page. Nothing is impossible with the Blood of a Succubus - by Ljuba Jeseník. The first thing that comes to the magician's attention is the name of the author, one Ljuba Jeseník. Only Patchouli would know that name, as she is the only one who Koakuma has trusted with her true name and the only one who knows why Koakuma calls herself Koakuma.
Ljuba Jeseník is a succubus who committed heinous crimes against fellow incubi and succubi. Rape turned to murder as incubi and succubi were brutally violated and as a result absorbed by Jeseník. This is why incubi and succubi have sexual relations outside their species but not within it. Jeseník escaped from her homeworld of Makai and found her way into Gensoukyou. She took the name Koakuma, referring to herself as an imp, rather than as a succubus. As they say, the rest is history.
The magician begins to read the pamphlet...
A succubus bleeds violently during orgasm. Blood released in this manner is white rather than red. The blood contains a part of the soul of the succubus that released it and through this part of a succubus' soul, a succubus can possess the being who ingests her blood. Even those for whom sexual arousal was impossible before can climax. But the fun does not end there! Drinking succubus blood and having an orgasm under its effects places one's body in a comatose state, while the soul is free to travel and make oneself visible to whoever they wish. Meanwhile, the same happens to the succubus whose blood was consumed. There are two ways to revert this false death.
1) If the physical body of the drinker has an orgasm. (This is always possible as they remain under the effects of the succubus blood.)
2) If the drinker and the succubus shatter each other's souls with another orgasm.
Should either of these occur, the drinker and the succubus will be forcibly returned to their bodies which will then be returned to life.
Patchouli lifts her head from the pamphlet and sees Koakuma kneeling in a suggestive pose, nude, fingers inside her, her crotch wet with a slick mist.
"I can help you..." The magician sees the bowl under Koakuma's crotch and immediatly deduces the meaning behind those words.
"Let's do it where no one can find us." Patchouli suggests. Koakuma stands up and picks up the empty bowl. They both make a run for a secluded corner of the library where no one will discover them.
Once they arrive at their destination, Koakuma almost begins to masturbate again, but at the last moment, realises that she doesn't need the bowl.
"Lady Patchouli, why don't you use your tongue?" Koakuma presents her other pair of lips and Patchouli simply eats it up. Even though she can't feel any sexual pleasure, she still knows that a girl likes to get licked down there. Plus, though she can't derive any sexual pleasure from it (yet), she can still taste the imp's sweetness. She does not feel more aroused than she was before. But that all changes when Koakuma groans about not being able to hold back.
"I hope you're ready, Lady Patchouli... Oh my! I can't stop it!" Koakuma falls limp as she fills Patchouli's mouth with the fabled succubus blood. The magician swallows, and for the first time, her body heats up. She withdraws her head from the succubus' crotch and watches her thrust her hips against thin air.
Koakuma's blood spills onto the floor. She is facing the ceiling as the pleasure has taken over her body. Patchouli rips her clothes from her skin and tackles the succubus, pressing her vulva against her servant's vulva. "Thank you! I've never felt like this in all of my years! It's time to let this newfound lust run wild!" The librarian's pleasure builds quickly, not a surprise when it's one's first time. But a succubus experiences the same sensations that are experienced by whoever drinks her blood. Koakuma may have possessed Patchouli, but the drawback is that this encounter will be short.
"I can't stand anymore of this, Koakuma. I want to reach the summit. I want you to..."
"Kill me!" The demon finishes the magician's thought. After much friction, both of them fall silent and their eyes go wide. They convulse and spurt fountains of blood, their last signs of life before they are freed from their bodies.
Koakuma weakly lifts her head and runs her fingers through Patchouli's hair. The magician's bright purple eyes have concealed themselves. But an apparition comes into the succubus' view and Patchouli's smile is the last thing that Koakuma sees before returning the smile and leaving her body.
Hand in hand, they phase through the walls of the library and leave behind the violent mess.