Mum's Art Book

In the summer holidays when I was 15, there was a day when I was feeling bored. I had been at home for the past few weeks playing video games and just lounging around, but there's only so much of that I could take. It was the early afternoon, and the hot summer sunlight shone through the blinds and into the house. My dad was at work, my mum and sister were out shopping, so I was home alone. We had an air conditioner but it did not work completely well, so inside the home it was still fairly hot. I decided to take off my singlet and shorts, leaving me in just my swim briefs. I sometimes wore my swim briefs in place of underwear as I liked how they felt. Also, they did not become too sticky when I was sweating. I grabbed an ice block from the freezer and finished it in minutes. I decided to go down to the basement to try and find something to do. I went down the wooden stairs and quickly turned on the overhead fans to cool the room. I managed to find some old board games and toys from my childhood, so I took those out and explored their contents for a while. When I had finished with the games and toys, I started putting them back where I found them. During this time, I noticed a black book perched on top of one of the metal shelves in the basement.  I reached up for the book with my right hand and pulled it down. It was a new art book, full of paintings and other artworks. On the inside cover, there was a sticky note with a message. As I read the message, it became clear that it was a birthday present for my mum. I flicked through the art book and found a chapter on nude paintings! I started to get excited and aroused as I stared at paintings of nude men and women in different poses and settings. As I poured through these paintings, my penis began to stiffen and my heart started to beat faster. While looking at the images, my attention was brought to a beautiful painting of a naked girl. The girl had white skin, long blonde hair, a slim figure, small breasts, and a tiny bit of pubic hair above her slit. She was in the bathroom, standing with her arms by her side and a shy look on her face. I guessed she was in her early to mid-teens, judging from her appearance. I was a bit shocked that such an image would be allowed to be published as I had a conservative upbringing. As I continued to stare at the girl, the painting appeared to look more and more realistic, to the point where I was starting to forget it was just a painting. It was like I was peering into a hidden world within the pages of the book. I could feel my penis start to get fully erect in my swim briefs, noticeably creating a bulge that reached the waistband. I took the book to a corner of the basement and sat down with my legs out. I put the book to the side, near my left leg. My right hand started to rub the bulge in my swim briefs and my left hand slid over the nude girl in the art book. I pretended that she was real and that my hand was actually sliding across her smooth body. Then, while still rubbing my bulge, I used my thumb and index finger of my left hand to 'pinch' the girl's nipples. I knew I was about to burst really soon, so I quickly traced my left index finger down her body to her slit. I rubbed the slit of the girl in the painting, slow at first, then vigorously. My right hand continued to rub my penis up and down through my swim briefs. I started to become completely lost in my masturbation session. The slit I was rubbing was no longer just a painting. In that moment, it was real and I felt like I was actually rubbing the slit of a teen girl. I could imagine her moan and sigh as I pleasured the girl in her bathroom. My right hand stopped on a down stroke as cum exploded out of my penis creating a large wet circle at the front of my swim briefs. I had rubbed the book so hard with my left index finger that some of the ink from the page had transferred to my skin. It was like I now had a part of the nude girl stuck on me! I breathed heavily as I continued to marvel the magical masturbation session I just had. I stood up and felt a small bit of cum flow within my swim briefs. I closed the art book and placed it back where I found it. I walked back up the stairs of the basement, still feeling the wetness of my swim briefs on my now soft penis. As I reached the top of the stairs, I looked back at the art book, perched on the shelf. I would be ready to return to it soon.