My Yui friend Yui-san is getting married soon. Her husband is a man who lives nearby and whom she treats like a real brother. They are a perfect match, but I can't congratulate them from the bottom of Kokoro... One day, my sister showed me her true face, which she has never shown to anyone before. Her appearance was incredibly lewd, unlike the usual pure Yui-san... "I'm going to marry him, but let's have lots of sex?"