"Tool of demonstration?" Xue Yin wondered aloud as Nik nodded and sat on the edge of the bed occupied by Klas. She was soundly asleep even with the ball gag covering her mouth and Nik thought of the approach to start the lesson. Going too biological would ruin the mood while doing Klas too sadistically would also affect the over-all temperament of the latter portion of the session. He pulled the chairs towards the four girl with a simple manipulation of gravity while his fingers casually stroked Klas's left thigh. A dildo was still vibrating within her snatch, but anyone would have gotten used to this form of 'torture' by now. The area beneath her crotch was soaked in green.

"So? What is this 'blowjob' and 'anal'?"

Gojira inquired in curiosity as she looked at Klas. Unlike the voluptuous women in the distance, waiting for Nik, Klas was a petite lady. Her figure, though, remained curvaceous even without huge tits. It was her squishy ass that attracted the most attention. Even on such a soft bed, Klas's ass managed to press and mash against the surface. Hearing Gojira's inquiry, Nik smiled. "Do you recall me licking you guys?" His words instantly pushed the girls into a cliff of awkwardness as he continued with a chuckle. "Don't worry. This is what I call broadening horizons. You all don't have to force yourself into doing this. I'll simply wear down your resistance."

"Strangely, that doesn't sound reassuring at all." Asami countered, pulling a wolfish grin from Nik as he manipulated the inscriptions in the room and dimmed the light. He then gently stroked Klas's cheek and laced his palm with an extremely slight amount of purity lightning! With a soft zapping sound, Klas woke up and instantly gazed at the dark ceiling before her emerald gaze fell on Nik. Her eyes widened in fear that her heart was all too familiar with, and she struggled against the binding once again.

"Hmmgh!"

She groaned as Nik mercilessly shoved the giant dildo into her mineral snatch. Klas showed a few features similar to Pavakā. This woman was malleable. The outline of the giant dildo was bare for all the girls to see, and they yelped in surprise. Even Gojira felt interested in Nik's actions. Unlike the three girls who were already losing their minds to lust, this slight amount of 'scent' only served to entice Gojira and workup her 'appetite.' Still, she was clearheaded and inquired akin diligent student. 

"What kind of person is she? A monster who turned human?"

She inquired, and for the first time, Nik felt a tiny semblance if Ryu'er within Gojira. Nik didn't deny Gojira's inquiry and explained with an encouraging smile. "This woman is also from the [Transmigration Paradise]. Her lineage is crystal-men, but her species is still unidentified."

Nik explained. Lineage was the entire series of evolution, while the species denoted the point of evolution. For instance, Prime Incubus was a lineage with Lust Imp only being a lower-tier species/evolution. Klas shuddered as she found that Nik had long discovered her origins. As Nik continued to explain the entirety of the situation to the girls, his hands did not stop for a single breath. His palm continued to grip the end of the dildo tightly, and as he pulled the giant tool, it instantly exposed its glimmering green surface with ropes of Klas's own fluids bridging her soaking cave and the edge of Nik's palms.

All the while, Klas's soft whimpers rang within the empty room that only furthered the accumulation of lust within the mind and bodies of the three girls. Gojira, however, leaned back on the chair with her legs crossed and her arms folded beneath her bosom. 

"Let's see what you got." She smiled in genuine curiosity while Nik nodded. Since the lights were already dim, Klas's nipples and juices glowed once again. It was as if her exotic nature encouraged others to continue teasing her. Once Nik had concluded the necessary explanation, he removed his clothes. There was not a shred of awkwardness in his movements that also made others feel natural and comfortable. If Nik himself became insecure, how would he even manage to teach the girls?

"We will start with the anal."

Nik whispered as he climbed on the bed. The moment Klas heard Nik's statement, her heart went cold while despair permeated through her entire being. Meanwhile, Nik removed the bindings around Klas's ankles and gripped both of her calves with a single palm! This was the difference between Klas's and Nik's physique. What Klas felt was a giant dildo was merely reminiscent of Nik's size when he wasn't an incubus. After two evolutions, his size had increased overall. If that wasn't the case, then his loving girls back in his homeworld could have gagged and choked on his cock without having a fatal experience. 

But...

Nik's eyes shone in expectations as he pulled Klas's legs up and raised her waist. Currently, Klas's body resembled a 'C' with her legs above her face and her erotic bits right in front of Nik. Closing the distance and sitting with his legs crossed, Nik now dug her mine with the rubbery shaft as he observed her anus twitching with every pump. 

Nik knew that anal experience was a slippery slope with much preparations needed. But there were many creatures in multiverse whose anuses were merely decorative! Crystal-men, such a Klas, was one of them. Crystal-men ingested the relevant crystals to keep their core running. Not a single bit remained to be wasted. This information allowed Nik to decipher the fact that crystal-men could be the race that was meant to be fucked in the ass! Even Brian wouldn't have thought that Nik would come to this conclusion after reading through his hard-earned notes. After a few more pumps, Nik removed the dildo and placed it on the edge of the bed.

And under Klas's widened eyes, Nik leaned down and parted his lips. His broad tongue licked the entire mineral juice soaking her asshole and the surface of her gaping snatch with a deep lick. This action also made the girls witnessing the act blush in shame. All of them had gotten their cave licked clean by this rogue, and only now they knew how lewd and erotic the act was! Even Gojira's cheeks flushed, but her eager gaze remained on the act as if unwilling to miss even a single frame of action.

Just like Nik thought, though a variant, Klas retained the significant traits of her lineage. Instead of the sweet taste that his body was wired to lick, Klas's juices were actually salty. This wasn't merely due to the difference of Nik's lineage that allowed him to 'taste' bodily fluids in terms of eroticism but also partly due to Klas. Klas ingested minerals, and her body's composition was heavily skewed towards emerald. This causes the basic taste to be completely different from those produced by beings of flesh and blood.

As Nik licked Klas in one smooth motion, he let go of her legs, making them drift apart in the air while he placed both of his palms on her soft butt cheeks and poked her anus with both of his thumbs. As Klas's breathing grew deeper with the sound of her sniffing nose filling the empty room, the other girls were already leaning forward and continued to observe the scene breathlessly. However, Nik didn't make it easy. How can he give Klas the satisfaction of an orgasm when she tried to move against him? 

"Little girl, you are lucky. Quite lucky. After all, how many people can claim to be fucked by the only Lust Apostle in the multiverse?"

Nik inquired with a wolfish grin while raising his right palm high and—

*Pah*

His palm struck Klas's left butt cheek, leaving a slight handprint before he gripped her ass once again, and instead of poking her anus, he penetrated it with both of his thumbs and stretched her elastic asshole as wide as he could. The inner wall of Klas's anus was glistening dark-green with a ripe fragrance. She wasn't a human and, thus, didn't have the problems a human female would have by continuously maintaining her hole. Seeing such a wondrous sight, Nik tilted his body and looked towards Klas with an expression that made Klas cry.

"Don't cry, sweetheart. You'll feel good enough that I can promise."

Nik was no saint, and now that he had his claws on Klas, he didn't intend to go easy on this prime woman. With her asshole still stretched, Nik leaned down and once again licked the surface with the broad of his tongue. Currently, the hole wasn't wide enough, and including his thumbs, Nik could only stuff two of his indexes. This was far from enough. Meanwhile, at the girls' side, Xue Yin yelped under her breath as Nik licked the rim of Klas's asshole while the remaining trio gulped. Out of them, only Shen Xiu was unabashed to let her lust fuel her palms and touch her bosom while she continued to lean forward and observed with a thirsty expression.

"Hnnngh!"

Klas whimpered as her body trembled. Common sense dictated that the tolerance of crystal-men when it came to pain, lust, and other forms of bodily senses were quite high, but each of Nik's actions casually reached the peak of her tolerance. Seeing the constant twitch of Klas's flower with green marring her skin once again, Nik raised his left palm once again and smacked her butt harshly once again, letting her strained groan shake the room before he pressed both of his thumbs against the entrance of her anus and sent his voice into the consciousness of the girls present, detailing on the basics of maintaining their holes. This was a piece of extremely sensitive information to girls, and instead of speaking it aloud, Nik felt right by stating it personally into their minds. This kind of knowledge wasn't present in this world, and the girls were already feeling quite embarrassed as it is.

While transmitting the holy sermon, Nik pushed his thumbs into Klas's hole while tonguing her snatch. It was warmer than usual and extremely firm. The moment his tongue slithered into her literal mine cave, Klas gripped around Nik's pleasure-driven entity and struggled her arms against her binding so that she could pull Nik's face into her snatch!

Meanwhile, Nik had already pushed in both of his indexes alongside his thumbs as they spread her tight anus from the inside, making the conditions right for Nik to ram his cock into her crystalline hole and dig deeper!

*Slurp*

Nik flicked his tongue against the bright green nubbin with her sensual fluids already dripping once again. Once Nik determined that this was enough service for a woman who had ill intentions against his life, Nik sat on one leg and raised his other to reveal his thick cock. From the partition of her legs, Klas's glazed eyes had already lost all her hopes as her body trembled and arched up with each heavy thrum of his hefty shaft against her wet holes. Just the size itself made Klas shiver in complex emotions.