When my brother and his wife had an unexpected business trip abroad, they asked if I could look after their niece, Mitsuki. She was surprisingly close and open, showing off her vulnerable figure. One day while relaxing in the living room, I caught Mitsuki masturbating. However, she wasn't embarrassed at all; instead, she teasingly invited me to join her!

兄夫婦が急な仕事で海外に行ってしまった。留守の間、姪っ子の「美兎」を預かることになったのだが妙に距離が近かったりみせつけるかのように無防備な姿をさらす。ある日リビングで美兎がオナニーをしているところに遭遇し、覗いているのがバレてしまう。だが、それは小悪魔姪っ子の見せつけ誘惑だった！