My wife and I recently made the decision to "reform" our house, which is what the Japanese call remodeling for some unknown reason. One thing I knew I wanted to upgrade was our toilet, so we hopped in the car and headed to the local TOTO showroom to check out their latest models. TOTO (short for 東洋陶器 toyo-tohki or Oriental Ceramics) is the largest maker of toilets in the world, and in the 80s they developed a toilet with butt-washing and bidet features built-in called a "washlet" which has come to define Japan almost as much as Akihabara, bullet trains and Sony. While the basic features are the same, the newest models do cool things like sense when you've entered the bathroom and hydraulically lift the lid while heating the seat for you, then a mist of ionized water cleans the bowl so it's nice and fresh when you sit down. (An LED flashes inside the toilet while the mist is released, which I found terribly cool, though I couldn't say why.) There are numerous options for cleaning when you're done, from the standard butt spray to various "massage modes," and when you stand up the toilet auto-flushes and cleans the bowl for you again. If you're interested in getting a washlet toilet, they're available in various countries including the USA. Getting one installed would probably involve hiring an electrician, unless you happen to have an electric plug right behind your toilet as nearly all homes in Japan do.
I went shopping for a butt-washing toilet.