Stroking your dick from behind

"You seem to have a lot of tension in this one spot...I'm going to try to massage and stretch it out, see if I can work it out," Keiko says innocently.

She begins to move her delicate hand slowly up and down your shaft—still pressed up close against your back and with her other hand on your inner thigh.

You are so surprised that you gasp out loud, before remembering Sara. You quickly glance behind you. Sara is still lying down and sunbathing silently—likely asleep.

"Do you feel some pressure being relieved?" Keiko asks sweetly.

"Uhh, yeah," you manage to say—though in truth your mind is more focused on her hand that's currently jerking you off underwater and her huge tits squished up against your back.

Her other hand begins to wander down your thigh before she stops and suggests that you turn around.

"It's easier for me to relieve a patient's tension if I can see where I'm working," she says, still keeping up the professional charade.

"Good idea. I think I could massage you too then," you say. You turn around, and her almond-shaped eyes twinkle at you as she begins jerking you off with both hands. Getting a handjob underwater is a strange sensation, but you're not complaining. Facing Keiko also gives you a chance to ogle her magnificent bra-less breasts. They're every bit as impressive as they looked in Sara's too-small bikini. They have the slight amount of sag that natural large breasts—she must be a DD easily—have, and have pointy pink nipples that beg to be played with. You cup her soft, smooth breasts in your hands—in the pool they practically seem to float—and start doing exactly that with them.

Mindful that her skilled hands could bring you to the edge at any moment, and not wanting to blow your chance with Keiko on a handjob, you slip your hand below the water and under her bikini bottom.

"Uh uh," Keiko says, and you feel dejected for a second. Then, she continues speaking. "Water is a terrible lubricant, let's get out of the pool and do this."

Seeing the look on your face change, she smiles and says "Therapist remember? Lots of anatomy classes."