Kosho （小姓） is the name of a post in a samurai family similar to a page or squire. It is also commonly written as 小性 which literally means "small sex."
The term is derived from the word 'kosho' or 'koju' (attendant of a noble person) which from the middle ages was a post that meant serving in close proximity to a busho (Japanese military commander) and taking care of daily chores and affairs.
During the Sengoku Period (period of warring states), Kosho took charge of secretarial affairs, in particular acting as a human shield to protect their lord at the risk of losing their own lives; for this reason, Kosho had to not only be knowledgeable and have impeccable manners, but also be skilled in the military arts. As they grew up, many Kosho demonstrated brilliant performances as a close retainers to their lords. Hideyoshi TOYOTOMI and Ieyasu TOKUGAWA took sons from daimyo lords as hostages under the pretext of taking them on as kosho.
In Edo bakufu (Japanese feudal government headed by a shogun), under the supervision of a wakadoshiyori (a managerial position within the Edo government), Kosho took care of the personal chores of the Seii Taishogun (literally, 'great general who subdues barbarians').
According to the organizational structure of the bakufu or Domain of each clan, Kosho secretarial roles involved being an officer who handled the domestic economy (Goyonin), working as an aid to the lord (Sobashu), an attendant to the lord (Kinju shuttoyaku), or being an assistant who announces visitors and conveying messages (Goyotoritsugi). Although the primary duty of a Kosho was to guard their lord, the main duties of a Kosho were to serve closely to their lord, doing daily chores and arranging visits by acting as a go-between delivering messages.
As Kosho were always stationed close to their lord, Konando-yaku (a job to do chores) was created for them to act as a foot page.
Many domain lords appointed excellent, young clansmen who had just celebrated their genpuku (attainment of manhood) to such positions as Kosho or Goyonin with the intention of fostering human resources to work as their hands and feet in the future.
For example, when a boy was born as a legitimate first son of a permanent chief retainer, he often started his career as a Kosho, advancing to a domestic econony officer and then eventually becoming a chief retainer, or beginning as a Kosho and becoming a chief retainer after serving as an apprentice to a chief retainer.
The son of a senior vassal was sometimes appointed to be a companion or close associate (Sobashu) to the son of a lord as a live-in Kosho.
In order to act as bodyguard and be trusted with important state matters, Kosho were put in the closest physical position to their lord, with some domains prohibiting them from having contact with other families, including their own.
In cases among hatamoto (direct vassals of the shogun) where there were a considerable number of retainers, second, third or younger sons, as direct descendants without a chance at being adopted by other families were treated as retainers of their hatamoto family and often appointed as groomsmen (Nakakosho) or stablemen (Nakaoku Kosho).
Sons in the same situation who were the descendents of a Daimyo lord, however, were given a paid rank (or paid position) and seldom became Nakakosho.
Alternatively, in order to reduce mouths to feed and give their sons an education, second and third-born sons of an impoverished samurai family were often sold to a Buddhist temple where they worked as 'Tera-Kosho' and took care of the personal needs of Buddhist monks.
In general, when a Kosho reached the age of 18 or 19 years old, they would collect their saved money and choose among such possibilities as buying Gokeninkabu (samurai status) or Ashigarukabu (common foot soldier status); becoming part of a merchant family (receiving economic support from them), be expelled from their temple and freed from their status as Tera-kosho; or if they became a householder with a wife and children, the marriage was neither legal nor officially recognized, therefore the children did not have samurai status and became common townspeople or farmers.
Male homosexual partners
There were times when Kosho were forced to be the homosexual partner of pederast lords (Kosho who were stuck with this duty, known in general as "the work of Kosho," were also called "Kogosho" which meant they were Kosho who had not yet attained manhood.
(However, this duty was not necessarily a common responsibility for Kosho.)
During the Sengoku Period (period of warring states), when a battle required a long stay at the front, a lord would choose attractive boys among his Kosho and practice various kinds of sexual acts with them, such as anal intercourse, in order to vent his sexual desires. Although this practice continued into the Edo period, as Genroku Culture came to its end during the middle of the Edo period, the practice of male homosexuality drastically declined.
Individuals in which there are letters of evidence
Shingen TAKEDA and Masanobu KOSAKA (in this case, however, there is evidence that the family name KASUGA (KOSAKA) was added to the document at a later time).
Masamune DATE and Katsuyoshi TADANO
Individuals for which there are secondary historical sources
Kagekatsu UESUGI and Naganori KIYONO
Nobunaga ODA and Toshiie MAEDA
Masamune DATE and Shigetsuna KATAKURA, etc.
Although Nyohon (sexual indulgence with women) was a serious violation of a commandment for Buddhist monks, since there was no direct prescript referring to male homosexuality, Tera-kosho were often targeted as a sex objects.
Famous figures who were once Kosho
* Except for above mentioned figures. The name of their lord while acting as Kosho is enclosed in parenthesis (). Details from the Sengoku period lack full credibility, however, because these figures are only from secondary resources which were written hundreds of years after their death.
(Kagekatsu UESUGI or Kenshin UESUGI)