Ellen, a college student in Tokyo, returns to her parents' home for the first time in a while, but she feels a little lonely because she can't really have a conversation with her teenage brother. One day, she happens to find a porn magazine in her brother's room, and in an attempt to tease him like she did when she was a child, she shows off her huge breasts without a bra and teases him, but this awakens her brother's dormant sexual desire. He roughly fondles her huge breasts and penetrates her, and she resists in vain as he cums inside her repeatedly, and from that day on, she is chased by her super-horny brother...