In addition to manners they are warned about any dangers at the destination. For example, they are warned about seedy areas or common scams.
Tour companies have a vested interest in ensuring Japanese tourists are good guests. It helps them to negotiate deep discounts with hotels and tour operators.
It seems to be working. Japanese were voted the best overall tourists by a 2009 Expedia survey of 4,500 hotels around the world. The survey ranked tourists by nationality. Questions about politeness, generosity, tidiness, behavior, and willingness speak the local language were included.
Canada and UK were ranked second and third. France ranked last.
Amazingly, Japanese were ranked the forth best tippers — despite the fact tipping isn't a custom in Japan.