Aikyu is a term meaning a form of territory in the early-modern times when the murauke system (a system of village-wide, collective responsibility for tax payment) was established. It refers to a state where multiple feudal lords are assigned to one village. As a village (go) was naturally divided, the situation was also referred to as "bungo" (division of go).
Although this ownership form was also found in territories of court nobles, temples and shrines, and vassals of domains, it was most typically found in Kanto region where chigyo-chi (territories) of the hatamoto (direct retainers of the bakufu, which is a form of Japanese feudal government headed by a shogun) with a small stipend (fiefdom) were concentrated, because the Edo bakufu obliged them to live in Edo (except for those assigned to provinces) in order to ensure the control of them. Aikyu was the form of ownership used for not only the territory of hatamoto, but also that of territorial lords, temples and shrines, and the bakufu.
Aikyu is also referred to as "ni (two)-kyu" in the case where two feudal lords share a territory, "san (three)-kyu" in the case of three feudal lords, and "yon (four)-kyu" in the case of four feudal lords. It is recorded that there were some villages whose territorial form was jusan (13)-kyu with the assignment of 13 feudal lords (even there is a record that a village called Owari-mura located in Oku County [present Setouchi City, Okayama Prefecture], a territory of Okayama Domain, was shared by as many as 26 lords during the Kyoho era).
This system is believed to have been introduced for such reasons as securing a well-balanced real income in proportion to the fertility of land and tax rate, inhibiting hatamoto from exercising their right to chigyo-chi, and preventing villagers from uniting by dividing the village with the presence of several small-stipendiary chigyo-tori (recipients of land revenue). However, some scholars say that despite the bakufu's intentions, this system, which made hatamoto difficult to control their chigyo-chi in a stable manner, impoverished them and consequently it accelerated the decline of the Edo bakufu which was sustained by the military power of hatamoto.
Administration management of village
Probably because of the murauke system, nanushi (village headman) and other village officers were appointed by each feudal lord. Therefore, it was theoretically possible for one village to have more than one person with the same status such as nanushi. In fact, there was no rule to prohibit village officers to assume more than one post under the different feudal lords, and therefore, one person was able to hold the post of nanushi in different territories. However, due to conflicting interests between feudal lords and other factors, different persons were usually assigned to the same posts such as nanushi in each territory, and such a redundancy often caused confusion in village policy as a whole.
Attribution of control
The feudal lords did not rule a village jointly, but each one had his own designated area of control. A village was not uniformly divided based on geographical distinctions (e.g. east and west and north and south); each territory was readjusted on a case-by-case basis in view of the conditions of its land (e.g. the land's fertility). Therefore, in a village whose ownership form was aikyu, the territory was fragmented like a mosaic. However, This complicated division sometimes hindered the mutual surveillance system called gonin-gumi (history of Japan) where neighboring families were obliged to watch each other. In addition to the gonin-gumi unit established based on each feudal lord's chigyo (enfeoffment), other units such as community-level "go gonin-gumi" (community mutual surveillance unit) were formed, and such a pluralism of the mutual surveillance complicated the village political situations.