"What bullshit is this? Did the sun fry your neurons by any chance?" I said after hearing the nonsense Millie said
"I'm not kidding, look at my tail here." Millie said and turned her back to me, allowing me to see that she had poked a hole in the back of her jeans through which a long tail with a triangular tip like an arrow protruded, only it was clearly fake as it was an intense purple color.
"Aren't you ashamed to walk down the street with this toy up your ass?" I asked her
"This isn't a toy, it's for real. See, that way you won't be able to doubt it anymore." Millie said and pulled her jeans down along with her panties, with that I saw that her ass was actually attached to the base of her spine. I was surprised and jumped closer to her looking more closely and instinctively grabbed her tail, but when I did it she moaned and said that her tail was sensitive.
"But how is this possible? How did this happen to you?" I asked
"I do not know. I dozed off a bit while sunbathing and when I woke up I already had a tail. I was really surprised at first, but then I started to like my tail and I don't want to lose it." Millie said
"I think it's best for you to go to a hospital to see what happened and find out how to get back to normal, if needed your tail can be removed sirurgicaly." I said
"No way. I already said I'm going to keep my tail and you're not going to convince me otherwise." Millie said as I expected, as I already knew she was very stubborn and when she wanted something it was almost impossible to get her to change her mind.
"Think about it, you won't be able to hide your tail forever. What will people think when they see you?" I said in one last attempt to convince her
I" don't care what others think and I don't intend to hide my tail. Didn't you see that I even adapted one of my favorite jeans so I can still wear it?" Millie said and I was forced to accept her decision. As long as she's happy, so am I.
After that we stopped our conversation and I tried to go back to what I was doing before she arrived, but it was hard to concentrate as she took all her pants, skirts and dresses and adjusted them all by opening a hole for her tail.
When I checked the time I realized it was getting late and it was almost time for dinner, but I was very sweaty after a hot day and decided to take a shower first, so I left Millie modifying her clothes by herself and went to the bathroom.
While I was taking a shower Millie opened the door and came in saying she wanted to take a shower with me. I let her keep me company and just continued to wash, but she came up behind me and started rubbing against me.
"What are you doing Millie?" I asked her
"I'm just washing myself along with you, it's just that I'm horny and you're so hot I wish you'd join me right here in the shower." Millie said
I was also a little excited and accepted her invitation, so we hugged and kissed while rubbing against each other. Eventually we both lay down on the floor and intertwined our legs in order to rub our pussies against each other. Millie then pushed putting her tail between our pussies and we both rubbed against it.
I don't know how sensitive Millie's tail was, but she was moaning a lot and was clearly loving the experience, and as she looked at me with a very lustful gaze I was surprised by what happened, as her eyes change before me and became completely black.
I waited until we were done, until we'd come enough to feel satisfied, only then did I tell her about the change in her eyes. Millie then looked at herself in the mirror and saw her own eyes totally black as darkness itself, but she also noticed that her vision was much better than before and so she could ditch the glasses she only used to read.
"What does this change in my eyes mean? Do you think I'll still change more?" Millis asked
"I don't know, but I'm definitely getting worried. Are you sure you won't seek help?" I said
"For now I won't do anything. No need to worry Emma, if things get bad I'll get help, and you're also here if I need it." Millie said
After that we just finished showering and went to dinner. Nothing else happened for the rest of the day and eventually we both went to sleep, me in just my nightgown and Millie slept naked.