When I was 14 I was an American living in Japan. I lived with my parents on the sixth floor of a nice apartment that overlooked a park and several other high rise apartments.
One day I was on the roof of our apartment sort of laying out in the sun and just getting away from my parents. Every once in a while I would get up and walk around and look over the wall at my surroundings. This time I noticed some movement in the window of the apartment across the street. I felt strange staring so I sort of faced my head slightly in a different direction and cut my eyes over to the window. I was shocked to see that there was a girl, completely naked on her bed right next to the window. She was laying on her back with her feet up in the air. I kept watching and she began to just roll around sort of putting on a show for me. She wasn't masterbating or at least I don't think she was. Just rolling around naked. I obviously got really hard. I hadn't discovered masterbation at this point in my life so I just watched until the show was over.
The next year I accidentally discovered how to masterbate in the bathtub. If you're curious, it was while I was rubbing soap on my cock and it just happened. The next thing I knew I had white sticky cum all over my chest and a little on my face. I was hooked from then on and did it daily.
I used the image of this girl I had seen across the street to jack off while in the privacy of my bathroom many times when one day I decided I would go to the living room window (while my parents were gone) to see if she might be there. The more I thought about the fact that she might do it again for me or might see me got me really excited.
I took off all my clothes and walked through the house naked for the first time. Wow this excited me beyond belief. I opened the curtains and looked up to the window where this girl's room was. There was no one there, but I stroked and came to an amazing orgasm. From then on when I was alone I would go to the window and repeat. This went on for a few weeks and then it happened.
The sun was shining through my window and I pulled up a barstool and sat there stroking and fantasizing about this girl. The sun was on me so I was very visible to anyone looking in. Of course, there were only a few floors of the apartment across the street that were above my level so I only had to keep an eye on a few windows. I really only wanted that girl to see me. After a few minutes I looked at her window and saw the outline of a girls head peering out the window. It was her. I was so tuned on and blew many ropes of cum all over my chest and hands during that session. She watched the whole time.
I put on many shows for her from that point on. She must have liked what she saw because she was even there when I could do it for her. She probably saw me do this 30 or 40 times over the next year or two. I would run into her out in the street periodically, but we never spoke a word to each other. I was embarrassed at what I was doing and she probably felt the same. One time I think her mother caught her watching me because I saw two heads in the window and one looked motherly. This time I was on my back laying on the piano bench with one leg up and one leg on the floor. I was using oil and alternating both hands and I made it last for 20 minutes or so. The girl never returned the favor and I never saw her naked during my sessions, but she sure enjoyed watching.