If he's thinking up Momo's ass, then yes!

"...come to think of it, I never did take you... um, there..." he muttered, blushing heavily at the thought of taking that step.

Momo chuckled as she shakily got up and grabbed the bottle of oil, handing it to Izuku. "Honestly, I'm surprised it took this long for either of us to broach the topic... But then again, I guess we were already having plenty of fun as it was," she noted, playfully booping his nose.

"Oh, like, can I be involved too?" Yuya asked, sitting up eagerly.

"Of course... I guess just lay back on the floor, and spread your legs?" Izuku suggested, already having something in mind. Yuya immediately obliged, mirroring the position she had had on the bench, but now on the floor.

Momo didn't even need to be told to get on all fours, her face right above Yuya's leaking vulva. She gave Izuku a sultry look, turning her head to do so, and reached back, pulling one of her ass cheeks aside to expose her anus. Izuku knelt behind her, pouring a steady stream of oil onto her ass, making her croon in delight at the lukewarm lubricant being applied directly to her puckered opening.

He then poured some into his hand, using it to stroke his cock, allowing some vitality to return to it, so it gradually stiffened some. Once his shaft was back to full mast, and properly slickened up, he moved to line it up. He hesitated briefly, knowing that this would be his first experience with anal. "...fuck it," he finally exhaled, pressing his tip against her anal ring.

"Please do~!" Momo grinned. Izuku then pressed forward, gasping at the feel of his dick sliding with some effort into her rectum. It was squeezing even tighter than Yumi's vaginal walls. He grit his teeth, pressing deeper at a slow pace.

"Mmm!" Momo moaned as she felt her anus open up to Izuku's welcome intrusion. Yuya seized up as the foreign feel of a phantom dick entered her own anus. She then shivered in delight as Momo lowered her face, and started licking Izuku's seed from her labia.

As both girls writhed and moaned from the sensations, both phantom and real, Izuku finally buried himself to the root, his first instinct to wait a minute before moving to give Momo time to adjust, but her being a genie rendered that unnecessary, so he planted his hands on her ass, and began moving, breathing heavily as he slowly and steadily began to fuck Momo's butt.

"Oh yeah... This is great, Master..." Momo crooned, before resuming her licks of Yumi's pussy. Yumi nibbled her lower lip as she rested her hands next to her head, clenching them into fists, trying to process the sensation of being licked while being fucked up the ass by a phantom cock.

"I've been missing out..." he grunted, gradually picking up speed as he squeezed her ass.

"Mmmhmm~!" Momo murmured in agreement, before sliding her tongue into Yuya's pussy, and wriggling it about in there, causing the sentient bimbo sex doll to mewl in delight and arch her back.

Izuku worked his way up in terms of speed, grunting at the tight feel of Momo's anus as Momo, finishing up with the cum in Yuya's pussy, pulled back, fingering her. "I'm your little butt slut now, Master~!" she chimed, before she started licking Yuya's clit, intensifying her spasms as well as her own minor convulsions as they shared in the pleasure.

"...nothing little about your butt..." Izuku managed to get out as he continued to fuck Momo's ass with a series of pleasured grunts. "...but you are right about being a slut," he added, barely hesitating as he understood Momo liked being talked dirty to... Though as a Sex Genie, she liked basically everything perverted. It was just a matter of what kinks Izuku wanted to indulge.

Momo hummed, her ass contracting around his dick, before she gave a muffled scream of release into Yuya's snatch, drowned out by Yuya's own unrestricted cry as she came with Momo, throwing her head back.

Naturally, this once again pushed Izuku over the edge, and he released another helping of his semen into Momo's sphincter, though it was smaller than the last two. That was to be expected, his testicles were tapped out. As he collapsed, Momo also crumpled beneath him, her cheek plastered against Yuya's intimate space, her head turned so she could breathe unobstructed.

"...I hope you two aren't expecting another round today," Izuku wheezed. "...I'm bone dry..."

"...I think you mean "boned" dry," Momo managed to get out between her own gasps.

"...like... Lame..." Yuya managed to giggle.