Mei's Kokoro was drifting away from her husband, who was devoted to his work. She started to Kokoro for me, her brother-in-law who lived in the same house, and a forbidden love gradually blossomed between the two of them... The two of them made a promise to only kiss, and their secret love progressed. However, my desires were unstoppable. As love and desire intertwine, Mei poured all her feelings out on me. Although Mei also had feelings for her husband, we finally passionately sought each other, crossed the line, and came inside her... Will this love end in disaster, or...?