My new sister Satsuki, whom my parents married. She was cute and kind, and we quickly became close friends. However, when she found out that someone had caught my eye, she suddenly transformed. Jealous Satsuki teased me by showing off her panties, which were always hidden before. Despite being good siblings most of the time, I couldn't resist crossing the line after being so aroused by her provocative actions.

両親の再婚で出来た妹鈴。可愛く優しい鈴とはすぐに打ち解けて仲良しのつもりだったが、僕に彼女ができた途端、妹が豹変。嫉妬した鈴は僕の大好きなパンチラを見せつけ誘惑。普段は中の良い兄妹だったがあまりの挑発に勃起してしまった僕は遂に一線を越えてしまう。