Have her dance for him!

"Got another one in you, Master?" Rias smirked at Issei as he caught his breath.

He wheezed slightly, and looked down at his semi erect manhood. "...I should, just... Give me a few minutes..." He then looked at her with a smile. "How about you give me a dance while we wait for "Little Issei" to get back in the game?"

"Oh, I like the way you think, Master!" Rias replied, standing up, her hands on her thighs as she rose slowly, trailing them up her lithe, voluptuous form. She stepped back, swaying her hips as she closed her eyes, smiling behind her veil.

Issei watched, awed, drinking in every movement, from subtle to blatant, her feet shifting weight. Her breasts gave several slight bounces, barely contained by that see through top, her nipples hard and straining against the silk. Her belly undulated as she rolled her hips, like she was holding up and invisible hula hoop. "Wow..."

"You like this, Master?" she asked, tilting her shoulders back to jut out her breasts more.

"I do," he nodded, actively drooling at the sight of her. The moment he noticed, he blushed and wiped it away, though she noticed as her eyes creaked open in a sultry squint.

"I can tell," she giggled, giving him a twirl, splaying out her arms as she spun. He glanced down at her shapely rear, as it came into view, and with a grin, she twirled again so he could have a better look.

"... you're really liking the fact that I'm enjoying myself, aren't you?" he asked, her show already working and causing his cock to grow hard once more, and she nodded.

"It's how I'm wired as a Sex Genie, Master... Serving is our very nature, hardwired in. And it really feels so delightful to see our owners pleased by us," she moaned, placing her hands behind her head, and moving her hips in more complex figure eight motions.

He gazed at the way her flesh moved, before he said, "Okay, stop. Get naked. I'm just about ready again..."

"Of course," she crooned, delighted to comply, her nimble fingers pulling her veil aside, and moving over her body to undo every bit of silk.