Looking around nervously, she removed her string bikini. The tiny cove rarely had sunbathers, but she trembled with anticipation nonetheless. Straddling the tank, she lowered herself onto the nozzle, then firmly twisted the valve. She felt the tickle of enchanted helium entering her most private threshold, making room for itself inside her body. She arched her back and pushed into the nozzle, letting her hips wiggle back and forth a little. A sensation of airy lightness grew in her rounded ass, slowly expanding upwards through her belly and towards her chest. She lightly touched her tummy, then let her hands drift around her torso and down to squeeze her backside. Her skin felt just like balloon rubber, barely inflated with plenty of give.
This was better than she had dared to hope; the description she had given the demoness must have been accurate. Looking down, she saw the tank shimmering slightly from the otherworldly spell. Just looking at it, touching it, knowing the contents were under so much magical pressure, had excited her; she couldn’t resist calling in sick for work the very next day to test her fortune.
The stretchy latex sensation spread up through her chest, into her shoulders, and trickled into her arms and legs. The hissing sound echoed in her hips, growing louder and more hollow as the flesh between her ears and the nozzle dissolved into buoyant gas. Her arms filled up to her fingertips; her legs tingled with the transformation as they pushed out to a neutral position, bare feet affixed to the tips of an inverted V. The nozzle alone held her remaining weight. Guided by her excitement, she firmly twisted the valve again and grasped the tank head. She would need to hold on soon.
As the last of her flesh dissolved, her latex skin began expanding. It started in her breasts; they bulged out, growing into symmetric spheres. As they approached half a foot each, their connections to her body started shrinking, until she had two perfectly round rubber bubbles growing from thin neck-like connections to her chest. Free to tilt, their lift pulled them upward until their tops rested against her shoulders. As her breasts continued inflating, pressure built in her buttocks. Reaching behind with one hand, she felt a pair of expanding hemispheres greedily blowing up with the special gas. Her remaining hand felt a subtle pull of lift where she held on to the tank — she was getting light, starting to pull upward. Returning both hands to the tank head, she gripped more tightly. She had a long way to go.
Looking down between her inflating breasts, she saw her tummy pulling taut. Each ripple of her abdominal muscles bulged, and the tension seemed to direct the gas to where it was most readily accepted. Every square inch of her skin tightened up as she inflated into a human balloon. She was increasingly certain of what would happen if she let go of the tank; the realization of being buoyantly light sent an expanding thrill loose inside her gas-filled body. She surrendered to the pressure: her eyes went wide, her lips puckered into an “o” shape, her hands held on tighter, and her pussy squeezed the helium nozzle. She was delirious with anticipation as she twisted the valve a third time.
Her breasts and buttocks inflated steadily, blowing up beyond a foot each. Eager to touch them, to caress her tightly expanding rubber skin, she restrained herself so as to hold on longer. There would be time enough for that after she let go, assuming all went as planned. Expanding breasts tickled her cheeks and face, making her desperate to touch, to feel the exquisite tightness. She closed her scissored legs around the tank, wrapping its magic with her bulging thighs and calves. The cylinder felt cold and hard against her sexy, expanding skin. She needed its power. She felt her lift increasing and grasped the cylinder head harder. Her hips gyrated in circles, nozzle up her pussy, lost in the sensation of inflation. Her breasts blocked most of her view, although they were becoming translucent as they stretched tighter, approaching two feet each; she could only assume her buttocks were similarly expanded. Moans of impatience, of desperation, escaped her puckered lips as her back arched rhythmically.
The rest of her body tightened up. Muscles bulged along her arms, legs, back, and shoulders. Her nipples poked out; her lips puckered more tightly, leaving a pinhole gap; and she even felt her anus squeezing tightly shut. Her pussy puffed up, involuntarily gripping its hissing guest. Her clit bulged, needful of attention. She twisted the valve one final time, reaching its rotational limit. Her breasts and ass stretched tighter, inflating into four transparent superspherical helium balloons. Her breasts passed three feet each, bobbing and boinging against her face. Her buttocks pulled strongly upward, expressing an immediate desire for flight. She barely held on.
Still her inflation continued. Her puckered lips puffed up so tightly that they closed completely, and her final moan of pleasure filled her cheeks to capacity like a ball gag. Her pussy squeezed the nozzle so tightly that it felt enormous inside her. Finally, the gas stopped; she had emptied the tank. Desperately eager for release, she let go… and stayed put. The nozzle was stuck inside her like a lead weight, concentrating the sensation of upward lift in her pussy. She needed to fly so badly; the pressure taunted her entire body, magnifying every sensation. Upward buoyancy filled her to the brim; there was nowhere else she could go. Unable to do anything else, she desperately bounced her overinflated balloon booty up and down for all she was worth. She felt the nozzle slowly pulling itself out of her bubbled body.
Suddenly, finally, the anchoring nozzle came completely free. Filled impossibly tight with excitement, she flew up into the air, four balloons rapidly disappearing into the sky.