Yeah, I think she's got this.

Rimuru's mind clouded over in pleasure. Despite Eren's inexperience, she was hitting all the right buttons. Though Rimuru's own inexperience probably helped bridge any gaps in her handjob form, and given how long he'd been in this world without any manner of sexual release, it only figured he wouldn't need much help getting off, at least for the first time. It was to the point that Rimuru couldn't focus enough to even entertain the idea of having her stop, or asking over any of the other women in the room watching the Ruler of Monsters receive pleasure to join in.

So Eren was left to continue on her own, only pausing briefly when a mostly clear, blue-tinted liquid began to leak from the slit of Rimuru's cock. She quickly identified it as the closest approximation of precum the slime's body could produce, letting it wet her hand as she resumed her masturbatory motions along the length of his member. She felt confident she was properly recalling what she read in books; proper lubrication was a vital step in ensuring sexual activity would be pleasurable for all parties involved.

Even knowing that, her curiosity quickly grew, or perhaps a natural instinct began to take over; her tongue reached out between her lips and made contact with the middle of Rimuru's shaft, before being pulled along the slime-slicked flesh. It ran across the glans and up to the tip before retreating back into Eren's mouth to focus on the taste of the slime, leaving Rimuru's cock to twitch wildly as he resisted a near orgasm right then and there. It was markedly sweet, much like the confections the many culinarily-talented residents of Jura-Tempest Federation often made in his likeness, which on some level made sense to Eren given Rimuru's own displayed propensity for sweet-tasting foods.

This sweet taste made the next step Eren knew she had to take much easier. She pulled the rigid penis a few degrees downward to make it level with her now wide open mouth, leaned forward, and wrapped her lips around the first quarter of his length, gagging once from accidentally teasing the back of her throat with it. She dragged herself back, her tongue scraping across the sensitive underside of Rimuru's dick, while her lips made a seal around the rest of its circumference. Upon reaching the tip, she teased the glans with her tongue, coaxing a twitch that she could almost feel trying to pull her entire body up off the floor, along with a squirt of precum that filled what was left of the space in her mouth.

Swallowing down the mouthful of sweet-tasting slime, her mouth made another trip down the first quarter of Rimuru's cock, not at all experienced enough to take any more of it in her than that. She'd repeat the motion, trying to speed up with each repetition. Before long, slow teasing became actual cock sucking, but with her hands still at work stimulating his testicles and the remaining three fourths of shaft her mouth couldn't fit, it didn't last very long.

"Ahhh...Hnnng! Oh, god, fuck, yes!"

Without the mental fortitude to berate himself for such cliché AV dialogue, nor to warn Eren of his impending orgasm, Rimuru lost himself to the pleasure provided by the insanely cute elf girl's hands and mouth, not to mention the delightful softness of the boobs his head and hands were still resting on and fondling. His cock throbbed with power as it ejaculated a jet of cloudy, pale blue slime straight into the back of Eren's mouth. Having been entirely unprepared, Eren pulled away and coughed out what slime hadn't already overflowed and squirted out past her lips during the initial spurt, then yelped as the next spurt struck her square in the face, her eyes thankfully having been fast enough to close before any of it got in them.

Eren, now with her face painted blue, released Rimuru's cock and ducked out of the way, leaving it free to launch the next jet of slime cum through the air. The sticky liquid fell over several of the goblinas making up the audience, eliciting a chorus of delighted squealing which continued as several subsequent spurts were launched over other individuals in the crowd.

Once his orgasm subsided, Rimuru slumped back in his throne of women, the softness of their bodies and their adoring giggles heightening the satisfaction of the afterglow. Eren lifted her head once the sound of Rimuru's moaning ceased, allowing her to wipe the sticky slime from her face and look around. She was greeted by expressions of happiness wherever she looked, whether that was at Rimuru, at the women supporting his spent body, or the monster women in the crowd sharing tastes of their lord's orgasm fluids with each other. Somehow, the sight of so many smiles served to succinctly symbolize the strength of their esteem. Even when taken over by lust, Rimuru was considerate of his subjects. Even when their ruler was acting odd, his subjects were still there for him. Such a debaucherous gathering should have felt impersonal or one-sided, and yet she could not find one person present who seemed displeased.

A smile spread across her face as well, the love burning in the hearts of the monsters of Tempest warming her own.

As the rest of the women enjoyed the aftermath of his orgasm, Rimuru's wits were slowly returning to him once more. And with that clarity came a realization: he wanted more. Whether it was his body or his mind telling him that, he didn't know. What he did know was that he had plenty of freedom to pursue his desires, and plenty of options with which to pursue them. So...