The human anus is a sensitive organ.

If you thrust in without sufficient foreplay, seeking both a sense of depravity and pleasure, the inner mucous membrane could be seriously injured.

Rustila seemed unaware of this fact. That's why she hadn't brought that essential lubricant.

So Eidel decided to take the lead. Though it was his first time too, he figured his knowledge would be enough to manage.

Eidel positioned himself with a cushion behind his back, sitting in an awkward posture. They were still in the 69 position. Rustila was preoccupied with practicing fellatio.

Let's see.

First, it would be good to heighten arousal by caressing the buttocks.

As he stroked up and down her bottom, teasing her, the pressure he felt below changed noticeably.

Rustila responded by suddenly tightening her mouth around his shaft.

"Ugh!"

This sensation was truly incredible.

If Zernya felt like a tight, moist space that tickled him, Rustila was like a vacuum that mercilessly sucked him in depending on her movements.

Neither could be called better than the other. Each had their own charm. However, Rustila was overwhelmingly better at quickly bringing him to climax.

Smack!

"Mmph?!"

When he slapped both buttocks simultaneously, Rustila jumped like a mullet. Since she still had his manhood in her mouth when she jerked her head up, the pulling sensation at the base sent waves of pleasure up his spine.

That was dangerous.

He almost came pathetically fast.

Strange. She should be inexperienced in sex. Yet without any prior training, her basic skills were excellent.

"Rusti, have you been practicing?"

"Puha...! N-no?"

Rustila shook her head as if wrongfully accused.

So it was pure talent.

She was already a genius with the Plasma Sword, and now it seemed her skills at drawing Excalibur were also top-notch.

Indeed, just as he had that thought, he felt a warm sensation on his testicles.

"Rusti, what are you doing?"

"Oh, sorry...! Did it hurt? I guess this isn't a place to caress..."

Needless to say, Rustila had taken his testicles in her mouth. She had been rolling them around like candy, sucking them fully into her mouth.

"No, that's not it. I was just surprised you'd go that far."

"R-really? That's a relief."

Rustila sighed with relief and continued her caresses.

It was time to move to the next phase.

"This will be cold."

"Okay, mmm...!"

Eidel spread lubricant widely around Rustila's puckered entrance. Her buttocks trembled intermittently at the cold sensation.

First, starting from the outside.

Then gradually moving inward, as if being drawn into a black hole.

He teased with his finger, almost entering but not quite. A voice drenched in pleasure came from below.

"I'm going to insert one finger at a time now. If it hurts, tap my leg immediately. Understand?"

"...Yes."

As if answering in kind, her rear entrance twitched.

Eidel poured an excessive amount of lubricant before inserting the tip of his pinky finger.

"Nnngh!"

As expected, it was tight.

But this was just the beginning.

Now came the time for patience. He had no choice but to loosen her up sufficiently by repeatedly inserting and withdrawing slightly until his little finger could fully enter.

***

Who knows how much time had passed.

Zernya rubbed her eyes as she woke up. Then she suddenly became alert at the foreign sensation in her lower abdomen.

Right, she had her first experience today.

Just remembering the magnificent sex made her body heat up again.

If it was that good the first time, a second or third round would allow her to feel even better and try various positions.

As she was reminiscing with satisfaction, another woman's coquettish voice came from right in front of her.

"Ungh, ngh! Eidel...!"

What was that sound?

Now she saw that Rustila and Eidel were right there, their faces buried between each other's thighs, licking frantically.

Zernya crawled over and looked at the panting Rustila.

"What are you doing?"

"D-don't... talk... to me... now... Ahungh!"

I see.

So it was anal play.

They had the rhythmical thought of using the back entrance since the front was off-limits for now.

"That won't be easy."

Putting aside lewd thoughts, this was medically quite dangerous.

But it might be okay, she thought.

What was Virgo if not one of the 12 zodiac signs?

According to her predecessor's records, it was the Darwin system's guardian. As strict about hygiene as it was about protecting virginity. Sometimes bordering on obsessive when necessary.

Moreover, as one of the 12 signs, it provided basic physical buffs. Not just strength, stamina, and agility, but also elasticity and recovery resilience.

Yes, there was no need to explain the general precautions.

Zernya decided to simply watch quietly.

"Haa, haa..."

By now, Rustila's bottom had loosened enough to take two fingers.

Eidel flipped Rustila over and positioned himself for penetration.

It wasn't cowgirl or doggy style, but a modified missionary position. Unlike regular missionary, her buttocks were raised.

"Do we need a condom?"

"It's fine, since I have Virgo..."

Amusingly, thanks to the constellation skill, hygiene wasn't a concern.

All that remained was how well Rustila could accept her husband's Plasma Sword.

Eidel applied plenty of lubricant to his manhood and aimed at Rustila's rear entrance.

"Here I go."

"Y-yes."

"At first, just put the tip in and then pull out right away."

Zernya advised. Eidel and Rustila looked at her.

"What? I'm just giving necessary medical advice."

Even if Rustila was a rival, she shouldn't get hurt during intercourse.

That was the righteous path Zernya had chosen as a doctor.

"But I've already loosened her enough with my fingers?"

"That applies even after foreplay, you fools. Especially you, do you even know how thick yours is?"

Eidel nodded.

They regained the mood and he aimed again.

"Hnnngh!"

Half pain, half pleasure. Eidel inserted just the tip and withdrew. Rustila breathed rapidly like someone experiencing respiratory distress.

Then a second, third, and fourth attempt.

"Ugh, ungh! Nnngh...!"

After more than a dozen attempts, the glans was finally accepted.

He withdrew again, let her rest with an anal plug inserted, then tried again.

About an hour later.

Squelch.

"Hnnnngh...!"

As more than half his length entered, a voice completely drenched in pleasure erupted.

Sweet as sugar and thick as molasses.

Zernya was surprised.

To think she could take something so thick so quickly.

If it were Zernya, she would have adamantly refused, saying it was impossible. She could see how intense Rustila's love for Eidel was.

"I'm going to move. Tell me if it hurts."

"I said... I will..."

Eidel continued adding lubricant and began moving his hips.

The rounded, relaxed entrance swallowed and released the massive object, moving like a living creature.

Rustila accepted Eidel in an awkward position, supporting her legs with both hands.

"Hah, hungh..."

Her arms were getting numb, and the adductor muscles inside her thighs were trembling. The abdominal muscles were also strained from maintaining the curved position.

There seemed to be some pain remaining. Eidel slowed his rhythm and moved his hand to the front.

"Ah, Eidel, what are you... Ahh!"

"This part is fine, isn't it?"

He exposed her clitoris with his middle finger and gently rubbed it with his index finger.

The female sexual nerve center, corresponding to the male organ, trembled helplessly under his finger's caress, screaming for the release of pleasure chemicals.

The dam of desire, which had been smoldering from the continued rear development, burst and released a flood of passion.

"Ah... ah, aaah...!"

After one magnificent orgasm, the feeling in her rear passage also became more intense. The stiffness gradually loosened, and the rectal folds soon adapted, writhing to better accommodate him.

"Phew, shall we change positions?"

"H-how?"

"However is comfortable for you."

"Th-then how about this?"

Eidel and Zernya both lost their composure.

The position Rustila suggested was doggy style.

With her chest pressed against the bed, she raised her buttocks and slightly spread them with both hands, waiting.

True to her military background, she was flexible and straightforward.

"...I-it's embarrassing, so hurry."

This was maddening.

With her begging like this, he had no choice but to give it his all.

"Ah! Aah! Aaah...!"

He freely moved in and out of the now accommodating entrance, pressing against Rustila's moan-generating spots.

True to anal sex, the tightness felt when entering and exiting was much stronger.

If he lost focus for even a moment, he might ejaculate immediately.

"Haaah...!"

Rustila felt like her mind had gone blank.

The sensation of her bottom burning as if being pounded with hot iron was commonplace, and the fact that she couldn't see Eidel's face mixed fear with pleasure.

That's why.

Smack—!!

"Aaahnnn...!"

When Eidel slapped her bottom hard enough to hurt, the arms barely supporting her upper body collapsed like a lie.

This didn't make sense.

After all those push-ups she'd done...

The spanking continued more than a dozen times after this.

It was a painful yet pleasurable sensation that could become addictive.

Around that time, her buttocks, which had turned as red as autumn leaves, began moving on their own to match Eidel's waist.

Squelch, squelch, squelch.

"Haaahn...!"

She felt it.

She was feeling it.

Why was a hole that shouldn't feel good giving her pleasure?

She felt a sense of depravity at her perverted self, and was also bewildered by her enjoyment of masochism.

In any case, with each thrust, she was approaching the threshold of climax.

"Rustila!"

"Aahn, in-inside! Come inside...!"

Eidel grabbed Rustila's hair, which had been swinging like a pendulum, and pulled. Her upper body, which had been lazily drooping, arched back, and her waist bent like a bow.

Splurt! Splurt!

After hours of charging, the ejaculated semen painted her rectum.

At some point, Rustila had been frantically rubbing her clitoris with her free hand, and in sync with his climax, she sprayed her juices.

As a result, the seal covering her groin fell off.

Embrace!

After a long battle, Rustila succeeded in extracting Eidel's semen.

"Rusti, are you okay? Does it hurt a lot?"

"A-a little..."

Semen gurgled out from her bottom, which was still throbbing.

This was no time to waste.

While keeping her buttocks clenched, she brought a special test tube and slowly poured in the extracted semen.

"...What's that?"

"They say we can use this for in vitro fertilization."

Rustila laughed weakly, spitting out hair that had stuck to her face with sweat.

"It would be nice to get pregnant directly... but this is the only option we have now."

"Then you didn't need to go this far. There was no need to do it this way, from behind..."

"I wanted to prove that this child was born from our love. Even in this way, at least we would know."

Eidel was deeply moved. Rustila exhaled and collapsed. After such extended foreplay and penetration, her strength was completely spent.

Eidel caught Rustila and stroked her hair.

"You did well, honey."

"Hehe..."

Zernya clicked her tongue.

She had to admit it.

There weren't many women who could do this.

Honestly, she felt a sense of respect.

"We should clean up soon."

"Y-yes."

"How do we deal with the bedding?"

Having used too much energy, they were hungry and dizzy.

Afterward, the three of them washed up, ordered a late dinner, and went to bed early.

***

And Sonia had been watching these three's lovemaking scene from beginning to end.

"Ah, young master..."