Riko and I have been neighbors since we were kids, and our parents are also good friends, so we're what you'd call childhood friends. Because we've grown up together, I've always felt like she was just a guy friend, and I've never really seen her as a girl. But one day, I happened to see the cleavage of Riko's huge breasts for the first time, and I suddenly became aware of her as a girl. To think that such a defenseless big-breasted girl was so close to me... Once I realized that, I couldn't stand it anymore. I can't stand it anymore, I want to have sex with this childhood friend of mine! Please, Riko! Let me do it!