Chosan was means of resistance and forms of struggle waged by farmers in Japan from the middle ages to the early modern period. It is different from the tobo phenomenon of fleeing one's birthplace during the ancient Ritsuryo period.
Before the Edo Period
Village residents (such as peasants) would leave manors en masse and temporarily take refuge in other areas where they would make demand that the feudal lord take actions such as the reduction of land taxes and the dismissal of the local governor. They would return once their demands had been met. The process was recognized as a lawful means of resistance in the event that a hyakusho moshijo (a written report submitted from a low-ranking person to a higher ranking person) was submitted, kishomon (sworn oath) was made and fixed procedures were adhered to.
The phenomenon increased from the period of the Northern and Southern Courts (Japan). During the Sengoku Period (Warring States period) (Japan), conflict meant that there were many people who fled due to suffering at the hands of bandits or pirates as well as many who fled in order to avoid heavy land taxes. It can be said that the capability of Sengoku daimyo (Japanese territorial lord in the Sengoku period) was measured by their ability to prevent such people from fleeing.
In 1488, the people of Kaga expelled the shugo (provincial constable), Masachika TOGASHI, and formed the monto-ryogoku (territory of followers). This Kaga Ikko-ikki Revolt is known as an example of revolt against a feudal lord.
During the Edo period, many chosan peasants generally left for urban areas where they lived on low wages. Since peasants were farm producers, their chosan led to a decrease in production activities. Therefore, the rulers (bakufu [feudal government headed by a shogun], feudal lords and direct vassals of the shogun) strictly forbade the chosan and generally did not recognize migration.
Since public versus private land tax tended to fall consistently throughout the Edo period (especially in government-ruled areas), it is thought that chosan was no longer serious issue. Nevertheless, there were cases of peasants using chosan as a means of demanding rights, and they flowed into to urban areas such as Edo. As a result, the population of poor people grew in urban areas. This led to urban problems, such as rising crime, which still continue to the present day.
* In some domains (such as the Satsuma Domain), the harsh exploitation of farmers throughout the entire Edo period meant that the conditions under which middle-class or wealthy farmers could become established never emerged. However, under extreme exploitation, some farmers would become ruined, which should lead to the concentration of wealth and the emergence of wealthy farmers. Therefore the reason why middle-class or wealthy farmers could not become established was land taxes which were sufficiently heavy to prevent farmers from becoming independent.
In present-day Japan, the resignation of public practice physicians is sometimes called chosan. It refers to hospital doctors who, forced to work long hours which violate Labor Standards Law such as working continuous 72 hour shifts, despair at the lack of improvement in working conditions and resign.
As a result of the Koizumi administration's medical expenditure reduction policy, working conditions for public practice physicians grew steadily worse. Exhausted physicians eventually chose to resign out of protest. There were often a chain reactions of resignations which had the serious effect of causing treatment systems of foundation hospitals in both rural and urban areas to collapse. Symbolizing the phenomenon and movement of medical care break down, the term spread on the physician's thread of 2 Channel (an online forum) from around 2005.
Hideki KOMATSU wrote about the collapse of the medical care system in "Iryo Hokai: 'Tachisarigata Sabotage' to ha nani ka" (Collapse of Medical Care: What is 'Walk-off Sabotage'). In his book, the author refers to the phenomenon of 'chosan' as 'tachisarigata sabotage' (Walk-off Sabotage). After the book was released, the latter term which sound milder became commonly used more.