Rimuru knew of ass play. Just a couple of days ago he had anal with the girls. However, he wasn't that familiar with his own ass. Even during his teenage years, he didn't experiment with his ass or prostate. Instead, he was mostly just a casual jerker, penis focused.
However, today, today he was moaning but the moans were somewhat muffled by Shuna's aggressive kissing. Shuna was also somewhat rubbing her belly against Rimuru's cock, diverting his focus to some extent.
Meanwhile Shion kept licking and sucking his asshole repeatedly. It felt good, really good and ticklish but- Isn't it dirty?
[Notice: it is not. It is in fact cleaner than your mouth.]
Unnecessary information. Rimuru tried to keep his sanity but it wasn't working. The more Shion licked his ass, the more his cock hardened and tickled. Even the occasional teasing rubs were starting to make him breathless. That familiar tingle grew and grew and then a hot warmth left his nether. "Mmh.." He'd just cum.
"So easy," Shuna giggled.
"He tastes really good," Shion said. "I think I might be getting addicted."
"Oh please," Rimuru said. "Get up, my turn," he said.
"Oh, by the way," Shion said. "Can you grow a vagina too?"
"Probably?" Rimuru said. "I don't like being a girl. Makes me feel like I'm using Shizu's body."
"I see… but," Shuna whispered. "It's still your body, you know. You can do anything you want."
"True," Rimuru said. "But no pussy."
Shuna giggled. "Okay. Not like we have cocks," She giggled some more and Shion joined.
Rimuru laughed too. They are obviously joking.
[Notice: It is possible for the girls to develop large cocks.]
Rimuru smiled and erased the thought from his mind almost instantaneously.
Instead, he transformed his penis into a multi tentacle cock thing and grinned. "Time for some fun, you mischief loving little kittens."
"Me-ow," Shuna smirked.
"Please go easy on me, mew…" Shion tried but was too embarrassed to commit. Her cheeks flushed a deeper shade of red and she couldn't even look Rimuru in the eyes.
"Of course," Rimuru winked and jumped in (not literally.)
His tentacle cock thing grew and formed two distinct cocks. Before he could do anything though, the girls both got on fours and raised their butts up toward him.
It fueled his tentacles to release that tingly goodness.
"You guys want to be butt-fucked?"
"Both holes please," Shuna said. "After your slithery vibrating double cock, I don't think I can go back to normal fucking."
"Me neither," Shion said, parting her buttcheeks."
That's going to be an issue. If they get addicted to this, normal sex would be impossible.
[Notice: It is still possible to go back to normal sex. It is more likely, the girls just want a fun, memorable wedding night.]
Rimuru agreed with that and grew two more dicks, moved them slightly to his sides like lego so the angle didn't feel weird to the girls and then produced artificial lube with magicules.
"Woah, what is that stuff?" Shuna said.
"It's so tingly," Shion mumbled.
Rimuru was using his fingers to directly inject the lube into their ass and pussies. "It's magicule infused artificial pussy juice. Has traces of feel-good hormones so might just feel extra good."
"But," Shuna pouted. "You still haven't started."
"Right, right," Rimuru said.
"Mngh!" both girls moaned as they took in the cocks; their yet lubed crevices welcomed the incoming hot rods. More tentacles formed and they wrapped around their thighs, bellies, boobs, and even necks, tickling their nipples, underarms and even ears.
"Time for loving fucking."
"Yeah~!"
"Fuck yeah!"