Watching Sis

This past summer my parents did some remodeling and had in a new walkin shower installed. It's really nice with two shower heads and a lot of room, it used to be a bedroom closet but they expanded the upstairs bathroom. The installers cracked one of the doors when they put it in and it was a week before they could replace it so we spent a week having to shower with one door missing. It really didnt matter as it was around the corner from the main part of the bathroom. One day I went into the bathroom not knowing my younger sister was getting ready to shower. I was at the sink when I heard the shower turn on. I looked around the corner and watched her step into the shower completely nude. She had her back to me and I saw her perfectly shaped ass. She turned around to get her hair wet and she had her eyes closed as I saw her perky little tits and her bush. She is slender with long black hair, probably about 34B tits and a neatly trimmed bush. When she got her shampoo I hid around the corner for a bit, then peeked back. She was rinsing her hair with her head slung back and I watched with fascination as the soap poured down her skinny body, over her boobs and between her legs. I crouched down so she couldn't see me and watched her soap her body then rinse off. I was really turned on and my dick was stiff inside my shorts. She turned off the water and I slipped back to the sink as she began drying herself. Shen she stepped around the corner she was wearing a towel with her hair wrapped in another one. She kind of stopped when she saw me and shrieked what are you doing in here? I said I had just come in to use the bathroom I didn't hear the water running. But I told her I did see her in the shower and told her she had a nice body. She said You were watching? I said yeah. I couldn't tell if she was mad or what, so I just said, its OK you really have a nice body and left the bathroom. The next day she said she couldn't believe that I had wtched her shower. I said if you want you can watch me shower. She laughed, then said really? I said sure. She said OK. We went upstairs into the bathroom and she sat in the chair in the corner. I stripped in front of her, pausing before pulling off my shorts. I stood there a couple seconds with my cock semihard and pointing straight out at her. Then I turned and went into the shower and turned on the water. I made sure I stood where she could see me and proceeded to soap up my body, turning so she could see my ass then turning again, soaping up between my legs and making sure I stroked myself a few times. By now I was rock hard and my dick was standing nearly straight up. I finished up and stepped out, reaching for a towel. She kept staring at my erection as I dried off. When I was done I stood in front of her and asked what she thought. She said interesting. I told her she could touch it if she wanted so she reached out and fingered my cock up and down then wrapped her hand around it and started stroking it up and down. I told her it felt really good and she took her other hand and started playing with my balls. It didn't take long before I could feel myself starting to cum. I asked if she had ever seen a guy cum and she said no and I said well your about to see it. Pretty soon I shot a load onto the floor and she sort of gasped but she kept stroking me until I stopped oozing cum from my dick. She grabbed my towel and wiped off her hands as I just stood there. I asked did you have fun because I sure did. She laughed and said yeah, then left. The next week she watched me again, then a few days later, after the new door was put on, we showered together and explored each others bodies. I'm hoping to teach her how to give a blow job and maybe even have sex, but I dont want to push it too hard I'm having fun as it is.