Wikipedia
Kagema (陰間) is a historical Japanese term for young male prostitutes. Kagema were often passed off as apprentice kabuki actors (who were themselves often prostitutes on the side) and catered to a mixed male and female clientele. For male clients, the preferred service was anal sex, with the client taking the penetrative role; homosexual fellatio is almost unmentioned in Tokugawa-era documents. The belief that the anus is a center of sexual energy that could be absorbed by the penetrative partner most likely originates within Chinese texts. Kagema who were not affiliated with an actual kabuki theatre could be hired through male brothels or those teahouses specializing in kagema. Such institutions were known as Kagemajaya ( ja). Kagema typically charged more than female prostitutes of equivalent status, and did a healthy trade into the mid-19th century, despite increasing legal restrictions that attempted to contain prostitution (both male and female) in specified urban areas and to dissuade class-spanning relationships, which were viewed as potentially disruptive to traditional social organization.
This increased interest in kagema derives in part from the increased presence of samurai-class men within cities. The garrisoning of thousands of male samurai in the major cities in the early 17th century not only brought the male-love tradition of nanshoku to the common people, but also dramatically shifted the ratio of men to women (peaking at 170 men for every 100 women), which limited the sexual possibilities available to young men and encouraged the spread of nanshoku among middle class men. Kagema themselves were immensely popular with the merchant class and wealthy elite of the Edo period. Many such prostitutes, as well as many young kabuki actors, were indentured servants sold as children to the brothel or theatre, typically on a ten-year contract. Kagema could be presented as young men (yarō), wakashū (adolescent boys, about 10–18 years old) or as onnagata (female impersonators). James Neill argues that the increasing commercialization of homosexuality in the form of kagema (in addition to increased western influences) assisted in the moral degradation of nanshoku. He argues that rather than representing a form of masculine selflessness, nanshoku became associated with moral stagnancy caused by urban entertainment districts.
This term also appears in modern Japanese homosexual slang.