Definitely one thing which you will be surprised in Japan is Washlet, electronic bidet. Washlet is a registered trademark of Japanese company Toto which head office is based in Kitakyushu. Toto is an inventor of bath module which consists of toilet, sink and the bath tub too. You can see bath module at almost any hotel in Japan.
Electronic bidet was actually invented in the United States in early 60s but failed to sell it. Toto imported the American product and later bought the patent and rebranded as Wash Air Seat but also failed. The product was too expensive and bidet function was not common in Japan. May be one thing which exists in European hotel but not in Japan is the bidet. Majority of Japanese do not know how to use it.
Washlet debuted in June 1980 focusing on three functions; rear cleansing, dryer, and a heated seat. Thanks to impressing TV commercial, total sales reached 30 million devices in 2011. Of course other companies followed later to sell the electronic bidet with different names. However, the name Washlet is much common than electronic bidet.
Electronic bidet was introduced to 14% of the households in Japan in 1992 but reached 71.3% in 2010. Not only in private residences, but you can find this device in hotels(if you stay in hotel which has a bathroom inside the room, definitely there will be electronic bidet too), restrooms of department stores, stations and other facilities.