A defenseless, busty sister gets fucked by her super-strong younger brother. She thought she was seducing her virgin brother, but... it turns out to be a surprise!

Hana and Tetsuya, who had lived nearby for a long time and were childhood friends, became brothers when their parents got married. When Tetsuya suddenly becomes a family, she is lonely when she is left with a wall, and she remembers the past and starts playing a doctor, but is surprised to see Tetsuya's cock that she sees at the time is unexpectedly large. He is curious, and proposes a doctor again and makes Tetsuya touch her huge breasts... From that day on, he was left with a blast from his younger brother's uncontrollable sexual desire...