He fucks her while they discuss details!

"You know what, I'm definitely down for that," Izuku smiled, getting off the bed, and undoing his pants.

"Let me help you with that, Izu-kun," Setsuna grinned, detaching her hands and floating them over to Mei, one pulling down her panties, the other pulling up her top, letting her nice breasts spill out.

"Thanks Setsuna," Izuku nodded, getting behind Mei, and lining up his cock as he stroked it to full erection. He pressed in with a single thrust.

"Ah... Yeah..." Mei murmured as he bottomed out in her. He began to slowly fuck her, and she crooned, each slow thrust making her dangling breasts jiggle. "So... I was thinking... Unh... Non lethal voltage, pepper spray, and maybe a capture net if I can cram one in?" she asked. "For the booby traps..."

"Mostly harmless deterrents," Izuku nodded, slowly speeding up. "Those should work..."

Mei bit her lip as he hit her g-spot. In the background, the other six were slowly stripping naked, transfixed by the show. They always enjoyed watching a new addition to the harem. If if it meant said new addition got the most attention for a few days. "As for the security questions..." she panted out, gripping the table with one hand as she continued to use her other to pencil in more details with the blueprint. She was surprisingly good at keeping a steady hand in this situation. "They should be something personal to you, easy to remember..."

"...I got one," Izuku grinned as he kept going, leaning over Mei and groping her boobs. "The question, what is a reasonable amount for a casual bet?" he groaned, kissing her neck, before stopping long enough to add, "And the answer is 100,000 yen..."

"Master!" Momo whined, dropping her bra as she did, making Tooru, and everyone who joined the harem after her blink.

"Um... Are we missing something, ribbit?" Tsuyu asked as she shed her remaining clothes.

Ochaco giggled, also finishing her disrobing at this point. "Master and Momo told me that they had made a bet regarding if I joined the harem, right before I did. Momo, not understanding how much money it actually was for an average person, initially suggested 100,000 yen..." Momo pouted at Ochaco.

"Traitor!" she protested, knowing the others would hold that over her head. There was a bit more laughter at her expense as she flushed.

"Oh, I'm definitely teasing you for that every chance I get," Setsuna giggled. By this point, Izuku was pounding into Mei, who was gasping, having written down that first security question. It was actually a good one, because the answer was so ridiculous, and the background for it so specific, no one outside the harem would ever guess it.

"I'm close!" she panted, setting down the pen down, her nether regions beginning to spasm around Izuku's shaft.

"So am I!" Izuku moaned, before giving a final thrust, and gasping as his seed burst out of his manhood. Mei cried out as she also came, her eyes rolling up and her tongue lolling out.

As the tension drained from their bodies, they slowly got their breathing back under control, and Izuku withdrew from her folds. "Mmmnh, nice... Okay, what other security questions did you want to put in?" Mei asked, regaining enough composure to continue.