如果你在你邻居的妹妹出差的三天里和她发生性关系......玛丽-立花。

原标题: DASS-434 もしも、彼女が旅行で不在の3日間、隣のお姉さんとセフレになったら… 橘メアリー

She was having an affair with a friend. Hajime, devastated, is approached by Mary, a novelist who lives in the room next to hers. Mary tells Hajime that she will comfort him, and they have sex. During the three days until she returns from her trip, the distance between the two quickly shrinks. They talk like lovers. They have sex like lovers. But their worlds are separated by a door. A different life that could have been, if one choice had been made differently. As many choices, as many countless girlfriends exist... The parallel world (multiverse) x Mary Tachibana finally begins.