Sadayo Island (貞世島, Sadayo-shima; Literally meaning "Proper World Island") is a heavily militarized island to the East of the Land of Water . It has its own government and is separated from the Five Great Shinobi Countries. It is well knowned for its heavy censorship as well as a dicator government.
The island was originally occupied by refugees who left the mainlands in search of peace, away from the shinobi. However soon many shinobi who seeked a life without constant battles of the mercenary groups and clans joined the island and began defening it from the invadors, in order to have a peaceful land without wars, thus they named it the "Proper World Island". Eventually the people of the island became so paranoid about keeping peace in the village that the military would not let anyone to go off-shore, in fear of information being released. As years passed the local government was formed, falling under a dictatorship of the Matsumoto family who originally formed the island's strongest defence unit in order to use it to their advantage of becoming the leaders. Over the next generation the island has trained the new shinobi in extreme and hazardous conditions.
By the time the third generation of the Matsumoto clan came to power, the people weren't as much thankful as they were scared of the regime- because of the extreme punishments and censorship imposed upon the civilians in order to protect the island and keep peaceful, nobody dared to rebel or go against the
Sadayo Island is an extremelly neutral country- they do not involve themselves into the business of other countries and refuse all political treaties in order to keep up their morale and to avoid making enemies for themselves. Other than general trade business, the Island is completely cut off from the outside world. Only the shinobi of the village have knowledge of the life outside, while the basic citizens are kept away from it and fed with propaganda.
The shinobi of the Sadayo Island undergo training like in all other countries, however the system is hazardous and sometimes even lethal to the students. All the shinobi are trained into complete loyalty and obsessive submission to the Matsumoto family, with many eventually becoming fanatics.