Sam stared at the image in the mirror. He couldn't believe that this beautiful girl was him. But the image followed every move he made an a short look down his body confirmed what he saw. His sight was bloicked by two breasts which were a B-cup as he guessed.
"This all must have happened because I put on my sister's bikini" he mumbled. "Therefore I should change back when i wear my own trunks."
He was about to leave to his car when it struck him that he was a teenage girl now wearing nothing but a bikini. This might do at the beach but wouldn't do outside. Then he remebered that there was a small shop at the entrance selling all kinds of items that might be useful for a stay at the beach.
He (or better: She) walked to the shop. She found a pair of swim trunks and returned to the locker area. She entered the next free one and started to strip down. Within some seconds the bikini came off.
Again she could have a close look on a developing female body and was intrigued to keep it. But she steeled herself and stepped into the trunks.
She waited eagerly for the cahnges to begin, but...