Tell her how breasts can be a useful way to stimulate arousal.

"You know, Grace," you say, "you just did a great job getting me aroused with your hand, and mouth, but do you know what can actually be another great way to stimulate a man sexually?"

"What's that?" Grace says, breasts shifting as she grabs her notepad, ready to learn.

"Breasts," you say, very seriously.

Grace glances down at her own breasts, then back at you. "What do you mean?"

"Well, sure, as you saw with Kuniko, looking at someone's breasts can help a man get aroused. But you could actually stimulate me and even bring me to orgasm with your breasts."

"How?" She asks, bemused, "You can't put your penis in them like a vagina or a mouth, and I can't grab you with them like with my hands."

"Let me show you," you say, crossing your fingers, "Would you please take them out?"

Grace looks to Diana for permission, and Diana gives her a shrug. So, the lovely blonde begins unbuttoning her blouse, revealing her ample breasts in their white bra. As she slips her blouse off, your penis aches at seeing her bar shoulders, and her perfectly smooth belly.

"You're beautiful," you say, "Now, if you take your bra off as well, I can show you what I mean."

She hesitates for only a moment, and then slips out of her bra. As her breasts fall free, revealing bright, pink nipples, you involuntarily take a step towards her.

"Do you mind?" you ask, reaching out.

She gestures you towards her breasts. You take one in your hand, feeling the weight of it, running your thumb over her nipple. You feel it harden slightly as you play with it. She isn't visibly aroused yet but she looks very curious.

"So, since you're sitting, and I'm standing, we're almost perfectly lined up. I can start by rubbing my penis lightly against your breasts..."

You step closer, and Grace leans in, arching her back slightly so you can press your shaft against her right breast. It's soft and gives as you push against her, pleasure running into you. You sigh as you gently grind against her a couple times.

"That feels good," you say, "but I probably wouldn't orgasm from just that."

"How would you orgasm?" Grace asks, hands sliding up to cradle her breasts, almost as if she's offering them to you.

You place your cock against her chest, between her two breasts. She looks down at your member and her mouth is only inches away from you. You feel a flood of desire just imagining her mouth wrapped around your dickhead, but you know that's not what you're doing right now. You slide your hands over her breasts again, giving her nipples a little squeeze. This time you notice a quick intake of breath from her. Putting your hands over her hands, you show her how to press her breasts inward, squeezing your cock from both sides.

"Ohhh," she says in sudden comprehension, "I see."

You begin sliding your shaft up against her chest feeling warm waves of pleasure as she firmly wraps your with her full breasts. You feel the pressure slowly building in you as you push faster and faster, watching your dick appear and disappear from her cleavage. She smiles, enjoying your building attention.