Unsure what was going on, Jack locked the door and stared at himself. His face looked totally different- he looked Asian all of a sudden, with subtly darker skin, a deeper shade of brown to his eyes and a more petite build. He pulled his T-shirt off, then his jeans and underwear, and saw that his skin tone had changed all over his body. Even his nipples had darkened.
A strange sensation raced through him as he prepared to pull his clothes back on. Slowly he realized more of him was changing than his race, and fear clutched at his stomach. Soon, that fear turned to something far stranger- arousal. His chest felt sensitive. His nipples had perked up in the cold air and the ring of skin around them seemed to be widening. And as he breathed heavily, mounds of fat and flesh seemed to emerge around his chest. These... these were breasts! Once they stopped growing, he tried to push them back into himself- and gasped as a pleasurable sensation ran through his chest. He reached to touch a nipple, which had both swelled up too, and had to bite his lip to keep from crying out. Fantasies flashed through his head about having people lick and suck at them, which felt alien and yet so intriguing. Maybe one day even a child would suckle on these?
Wait... a child? I can't breastfeed a child! I can't even HAVE a child! Jack thought to himself as reality returned to him for a moment. Then reality began to alter to fit how his body was changing, and he felt another intense arousing sensation seize his penis and testicles and reshape them before his eyes. He saw his shaft twitch and then start to shrink back into him, and felt his testicles pinch up and with two wet pops slurp up inside his body.
At this point, with Jack's male organs altering into their female counterparts, his castration and emasculation set in. She slowly felt herself accept that she was female now, sensing how his testicles were adjusting into her ovaries, his penis was receding to form her clitoris, and his scrotum was unsealing to form her vagina. Her sexual fantasies were transforming too, as she imagined a handsome man fucking her and cumming inside her, filling her with his warm sperm. The idea of someone's penis inside her made female juices drip from her slit.
As the changes finished, Jack saw her Asian woman's body and blushed, trying to hide her breasts and crotch from her reflection with her hands and arms. To her relief, her discarded clothes included a bra and panties as well as a casual top and pretty skirt, and she hastily pulled these on before heading back to her seat.
While sitting on the plane, she realized she was having thoughts in a different language besides English- she still understood that language, but it wasn't her native tongue anymore. Thai, she realized, was. And this flight was going to Bangkok. Kinda fitting that she had turned into a woman on the way, then, she thought to herself.
Jack might have hoped for an uneventful rest of the flight, but instead...