"We want you to have our child," her older sister and her husband ask Mako, so although she is confused, she decides to make her sister's dream come true. However, things don't go smoothly, and before she knows it, her sex with her brother-in-law becomes more frequent and intense. Eventually, even when her older sister is in the next room, her brother-in-law starts asking for Mako and ejaculating inside her, showing off to his older sister...