The Mukai siblings lost their parents at a young age. The older sister, Ai, continued to strive and graduated from junior college, becoming an OL. On the other hand, her younger brother Taiichi had a habit of playing around and didn't study much, but Ai cherished him as her only family member. One day, Ai received a call from a man named Nakata: 'Your little brother messed up our boss.' Summoned to make amends, Ai was trampled upon in front of her brother by Nakata and his crew, and further pressured into having sex with her brother…
