Voyeurism

"Mnh~ Mnh~ Anh~!" Reina moaned.

After Rudy turned on his piston and began humping Reina, Reina couldn't stop moaning.

When Rudy realized that she was feeling good while being watched, Rudy thought it would be the best time to increase the pleasure.

Still, Reina had covered her mouth with her hand at first, but when that didn't work, she pulled Rudy close and locked her lips with his. However, her moans were still muffled.

Rias was mostly a human with the basic vampiric abilities and features. Hence, she also had a super hearing, and even the muffled moans of Reina were audible to Rias— crisp and clear.

She was curious and wanted to watch them having sex, so she first glanced at them from the corners of her eyes to see if their faces were in view, but after confirming that only Rudy could see her, she slowly turned around without making any noise and watched the show.

Rudy was surprised, but he was close to shooting his load, so he kept quiet and focused on humping Reina.