Odette had gotten the naughty book from the maids about two weeks ago.
When she tried asking the maids about what the book was about, they blushed, but refused to tell her.
When the confused Odette handed it over to her sister for the first time, Odil had shut the book in a hurry after reading only a few chapters.
"Why'd you close it? What happened?" What's it about? Is it a forbidden book? Or maybe a satanic book?"
"Odette, you shouldn't be reading things like this at home. It's also not the kind of book that you should be casually reading with a cup of tea.
"Huh? What's that supposed to mean?"
"It's a book about the bodily relationships between men and women."
Odette gasped in response to Odil's solemn face.
"Then maybe it's…?"
"I've only had the chance to see it a few times… Maybe this is a guide for 'that'."
"What does it say? I also want to know! Tell me!"
"Pictures of male genitals. Naked women as well."
"No way…"
Odette's lovely lips lifted a bit as if she was thinking deeply about something.
"Could this be coitus–?"
Odil quickly covered her sister's mouth.
"You can't just say something vulgar like that! Don't you remember that time you got scolded by master? Besides, I haven't even fully confirmed it yet."
She hugged Odette close and muttered underneath her breath as if she was worried that someone might overhear.
"Before we get caught, let's hurry up and hide the book somewhere. We can just go back and check it out later."
Odette and Odil carefully sneaked back to their room with the book still held within their arms.
Was it how those smugglers from the 'Border Town' felt?
It felt so thrilling and fun to them that it reminded them of that night when they had snuck into Tarot Town for the first time.
Once they got back to their room, the twins placed the book on their desks when they sat down facing each other.
When Odette noticed that Odil stopped paying attention to her while lost in thought, she quietly began stretching her hand out towards the book.
"Hey, sis. I-I also want to look at the book for a bit."
"No!"
"Ow, it hurts! You didn't need to hit me like that! Didn't Big sis already take a peek!?"
Before Odette could reach the book, Odil had smacked her hand away in order to stop her from opening it. Afterwards, she attempted to convince the fuming Odette to calm down and wait for their chance.
"Odette, do you remember?"
"What?"
Her poor, teary-eyed little sister still felt wronged as she caressed her hand.
"That time when I snuck cookies from our teacher's cupboard the other day."
"Yes, you had stolen the whole thing and pinned the blame on me when you got caught!"
"No, no, not that part!"
Odil barely managed to calm Odette down again, who had already began screaming.
The reason why she brought it up wasn't to make her angry again.
"When we stole the cookies, did we eat them on the spot?"
"No?"
"Then when did we eat them?"
"At night."
"Do you remember why we ate the cookies at night?"
"Sis said it tastes better with warm milk… Huh?"
It was an excellent teaching style, similar to how Professor Amelia taught them in her lectures by asking repeated questions in order to receive the correct answer.
In order to prevent such a wonderful toy from going to waste Odil had used a roundabout method like this to convince her younger sister.
"Then…"
"Yes, not only is this book about sex… but it also describes the male body in detail."
"So if this book is a cookie, then what's the milk?"
"Of course, the milk is a man."
After hearing the word 'man', Odette's flushed face darkened even further.
"But how? Usually just the mere sight of us makes guys run away."
"I already have a plan, you idiot."
"What! Don't leave me out of it!"
"Then come closer and listen."
Odil pulled Odette's close as she pressed the book down.
That was the entire course of events that led to what Siwoo now has to go through.
2.
Unexpectedly, Siwoo had become some sort of teaching aid for sexual education.
Odil, standing close by, started to speak.
"Alright, Odette. Open up the book."
Odette swallowed her saliva in suspense.
She had been restraining herself from opening and reading it for the past two weeks for this moment.
"I hereby write this book for all of the innocent daughters of Gehenna to have a happy first night."
Odette began with the book's first page, reading the contents out loud..
"Table of contents…"
"You don't need to read the table of contents. It starts with Chapter 1."
"Hmm, sis. The first step to making love."
The essence of the book was just as anyone would have expected.
Not much was different between life in Gehenna and living in the Renaissance era.
Since there wasn't any form of free public education, ordinary citizens had no way to learn about sexual education other than books like this.
In other words, that book served as a manual for men and women who wish to spend their first night together without any mistakes.
While others who had used this book were usually young couples, Siwoo was being used as some kind of human dildo for sex education.
Fortunately enough, the book itself was very thin and likely wouldn't have much information due to the illustrations scattered throughout, not counting the excessively large font size.
"Unlike what you thought, the love between a man and a woman isn't about just giving each other flowers, watching a play together, and taking a moonlit stroll… Something else that a man and woman must do is to go beyond whatever they had promised to each other and spend an ambitious night together.."
"Wait, Odette, you're taking way too long. Can't you just get to the point already?"
Like Odil, Odette also seemed disappointed by how boring the book turned out to be.
But before she could even turn to the third page, she began to let out a hiss while her eyes opened wide.
"What happened?"
"I-I can't read this, Sis."
"Give it to me."
Odil quickly snatched the book from her hands as if she couldn't wait another second to read it.
She cleared her throat once more and began to read the book out loud.
"A man's genitalia is made up of unique muscles that expand when he senses sexual excitement. This process is known as an erection, and it is something required for a man and a woman to be able to completely connect."
"But what even is sexual arousal? How should we do it?"
Odil furrowed her eyebrows together, looking as if she had just been asked a very difficult question.
"Yes, what are we supposed to do?"
Even after Odette and Odil put their heads together and thought for what felt like an eternity, they still weren't able to come up with an answer.
In the end, the conclusion Odil had come to was…
"Let's just ask Mr. Assistant."
"I also thought of that just now!"
Siwoo felt like screaming when he heard the conclusion the twins had come to.
He had no clue what kind of sin he had committed in his past life, and he couldn't even begin to imagine just why he had to endure so much humiliation, such as being forced to jerk off in public or even getting a handjob in front of an audience.
"Well, you've already seen enough of me at the academy, so let's just stop here, okay?"
"Do you think you're in a position where you can talk back to me?"
"Well, not really, but …"
"We've known each other two years already, and since I'm such a pure and kind witch, I don't want to be forced to punish Mr. Assistant so severely.."
Odil began shedding crocodile tears.
Despite her mischievous personality, while at the academy she gave off the impression of a respectable noble girl. But when he saw her outside of the academy, he realised just how much of a tyrant she truly was.
"Come on, tell us already."
He had never been married, much less ever had a daughter, so he wasn't experienced in this type of situation, and in that type of situation, it was as if one day his daughter came up to him with an innocent look and asked, "How do you make a baby, daddy?"
"Oh, that's, uh. Sexual, hum, arousal is, um…"
Odette shouted out of the blue as Siwoo struggled to open his mouth.
"Oh, sis! Here's the rest!"
"REALLY?"
Like a starving rodent who found a hidden piece of cheese, Odil clung tightly to the porn magazine.
Reading a book that had already gained widespread recognition was much more trustworthy than listening to someone else's opinion in their eyes.
Siwoo wrinkled his nose after being neglected.
"First and foremost, this is manhood before arousal.
"Shall we compare?"
When Odil gestured in his direction, Siwoo's underwear fell off in an instant and went down to his ankles.
He could feel the twins' intense attention on his dick, which gave him a stinging sensation.
Odette put the book right next to Siwoo's limp dick and began to compare.
"Is it really similar to the picture?"
"It's a pity that it looks limp."
Odil and Odette exchanged giggles.
"So, this sexual arousal or something like that is what makes it bigger? But the other day, Professor Amelia made it big by caressing it with her hands."
"Let's knead it this time!"
In an instant, the twins took off their gloves and began fiddling with Siwoo's flaccid dick.
They were able to see it in class but never had the chance to touch it.
At the same time, Siwoo had gotten startled by the unexpected touch he felt in his sensitive lower half.
"It feels kind of soft."
"Yes."
It was different from Amelia's hand technique.
All they did was knead it as if they were a pair of children playing with clay.
After all, what was there to expect when they didn't even know what sexual excitement was?
That's why his dick was still limp.
The twin's hands continued to roam lazily here and there as if they were annoyed upon seeing the limp dick.
Siwoo sighed in relief.
"Why isn't it getting bigger?"
"I'll answer that question for you; men, too, have different kinds of problems, so when they're not in the mood, they lack vigor; and that's all for today's sex education…"
Odil and Odette, who had initially seemed to be paying attention to Siwoo, eventually lost interest and resumed reading the book after realising all he was trying to tell them was to stop.
"Oh! Sis! Look here!"
"Where? On the first night, men can get extremely excited and nervous. In that case, the male member may not get hard. So, first, help them relax with a hot kiss."
"A kiss?"
They tilted their heads in the same direction at the same time.
"What does it have to do with it? Kissing is done with the mouth, and the manhood is located down there."
"Let's do it for now."
With frantic breathing, the twins turned to Siwoo at the same time.
Siwoo preferred to close his eyes quietly.
If he had sex at this rate, he'll surely die.
He must never, under any circumstances, let his dick become erect.
They wouldn't be able to have sex unless he got an erection.
"I'll try it first."
"Kissing is something done between lovers, Ms. Odil."
She didn't take his words seriously.
"Well, then, let's love each other from now on."
Odil plopped onto Siwoo's belly.
She untied the ribbon that was looped around her chin, removed her bonnet, and slowly moved closer to his face.
A lofty nose and large eyes that were open even while kissing.
The smell of Odil's sweet breath tickled the tip of his nose as her thick lips approached him.
Even when he looked up at the face from that angle, he couldn't find any flaw at all.
He would have enjoyed their kissing, if it wasn't forced and he wasn't tied to the bed with his dick hanging out.
Odil and Siwoo's lips overlapped.
It was softer than marshmallows and wetter than dewy petals.
Her eyelashes could be counted from a distance as her eyes twinkled like jewels with an inquisitive energy.
Sadly, the lips that had been together for three seconds soon parted.
"Sis, you have to put your tongue inside while kissing."
"Tongue? That's nasty."
"But it says here that the side receiving the tongue should be softly sucked in and twirled around, as if melting a candy."
"Alright."
Odil, who received quick feedback, kissed him again boldly.
But later it was different; her sharp tongue poked through Siwoo's tightly shut lips.
Odil's round eyes were twinkling right in front of him.
The awkward tongue movements stimulated not only the top and bottom of the tongue but also the lips and every corner of the oral mucosa.
Odil's saliva tasted like a fresh orange for dessert.