Due to downsizing at the company, I am currently unemployed, relying on unemployment benefits to get by for a while. Suddenly, a beautiful girl moved into the room opposite mine. From my room, I could see everything over there through the window. It seemed like she was unaware of being spied on, carelessly having sex with someone right by the window, allowing me to admire her perfect body. After observing for a while, I noticed that the man with her was not her husband, he always arrived at 3 PM, and the frequency of his visits was decreasing. Today was the day he still came to have sex with her. But as I waited, no one showed up, and suddenly she noticed me and called me over. Her name was Suzume Mino, and she knew I was spying on her. Thinking that Mino-san would be angry, I knelt down to beg for forgiveness. But contrary to my expectations, she was not angry at all, but even wanted me to... practice the cowgirl position with her! The thing is, Mino-san is the mistress of that man, he always complained about her poor sexual skills, especially in the cowgirl position. Mino-san thought that was why he was getting bored of her and visiting less. She wanted to improve her sexual abilities and make the man feel more pleasure. And that's how I became the tool for her practice. I was only allowed to lie still while she rode on top of me. But gradually, she seemed to accept me more, no longer doing everything herself but letting me take the lead, enjoying the sexual pleasure together...