...A sub's collar. You were a little surprised by it. Who would be sending you this? You think about it and smile. The only one that you could think of was Lisa. She was a nice woman at work who liked to be a Dom. She had even told you that she would make you her sub one day. Your cock started getting hard thinking about it. She already had a female sub and you guessed that she wanted a male sub. You looked at the collar closely. It was a gold plated metal collar with pink stones set at regular intervals in the center. The inside was softly padded so it should be pretty comfortable. There was a lock on it of course and a ring for a leash. Smiling you eagerly put the collar on locking it. You turn to look at yourself in the mirror. The collar looked odd on you. You hadn't seriously considered being a sub before and maybe that had something to do with it. Looking at the clock you smiled. You had a little time before you had to meet your Mistress.
A couple hours later you left your house and walked to the park. It took you an hour to walk there but it was a nice night. You made it to the park at fifteen till eight and it took you another fourteen minutes to reach the fountain. Once there you were surprised to see a young woman sitting at the fountain. She looked like a nineteen year old Lisa so she must be related somehow. She looked at you and smiled saying "Well you're on time. I was getting a little worried that you wouldn't be here on time for the change."
You were about to ask what she meant when a jolt went through your body. After the jolt pain lanced through your body like you were burning from the inside out. You screamed once and fell onto your side curled up in the fetal position. Through the pain you could feel your body changing. You felt your feet, legs, arms, and hands slim. The hair on your body receded into your body. Your hips widened and waist thinned while your stomach flattened. You could feel your face rearrange and your hair grow longer. You felt your Adam's Apple shrink while your chest expanded into breasts. You felt your cock shrink and your balls pull up into your body. You felt your now really small cock slide down between your legs and a pinching sensation around it.
The pain suddenly subsided and you were able to look at your body. Though you didn't get long to examine it since the young woman clipped a leash to your collar saying "Come along my pet, it's time to go home."
"What?" you asked a bit too stunned to say anything else.
"I'll explain later after the shock has worn off" the young woman said. "Just know that I'm Lisa, your Mistress, and your new name is Elizabeth. Now stand up so we can go home."
You decided to go along with it for now. It was probably the only way you might get answers as to why you changed into a girl. As you stood up you saw that you had lost some height now being slightly shorter than Lisa. You also think that you're younger too so you ask "How old?"
Lisa turned toward you with an angry expression and said "When you ask me something you need to say Mistress. Like with what you just said it should have been "How old Mistress?". If you don't then you will be punished. Do you understand this my pet?"
"Yes... Mistress" you said a bit hesitantly. You didn't know what punishment Lisa might dole out to you but you knew you didn't want to find out.
"That's better" Lisa said. "As for your question, you're now nineteen again just like me except you've been made into a female. Now we're going home." She yanked on the leash causing you to stumble forward in your now too big shoes. As you followed Lisa you had to wonder what was going to happen now.