The introduction of the automobile in the 1960s brought with it the "motel" and further spread the concept. Japanese housing trends at the time were characterized by small homes with sleeping areas being used as common areas during the day and, as a result, little opportunity for parents to engage privately in intercourse. Married couples therefore began to frequent love hotels. By 1961, there were around 2,700 "tsurekomi" inns in central Tokyo alone. Hotels of the time featured unusual attractions such as swings and vibrating beds. The Meguro Emperor, the first castle-style love hotel, opened in 1973 and brought in an average of approximately ¥40 million monthly.