Naoto has a beautiful stepmother and step-sister due to his father's remarriage, but he feels anxious about the constant distance between him and his step-sister Yui. One day, he suddenly looks at his carrier and finds a mysterious app that can tell him everything about the other person. When he immediately uses the app on her sister, he ends up taking over her sister's body. He returns to his sister's room, confused, but when he sees her sister's body reflected in her full-length mirror, the lust he had been suppressing comes out. Unable to hold back her lust, he began to touch her firm breasts and swollen nipples, enjoying the pleasure of a woman he had never experienced before.