IESP-666 I fell in love with my husband's sister Mai Kamisaki is now a lesbian

I want to get married after a long relationship with my senior at university. - My husband had a younger sister, Hibiki, who was the same age as Mai. - One day, Hibiki rolls into the newlyweds' house. - A few days later, Mai's husband goes on a long business trip overseas. - Hibiki consoles the lonely Mai. - Mai gradually becomes attracted to Hibiki...