Wakaresaseya (literally “breaker-uppers”) is the nomenclature or slang for Japanese businesses that specialize in drawing an individual into an affair. Though most often used to gather evidence of infidelity for use in a divorce case, it may also be used for purposes ranging from bringing shame to someone or securing a resignation of an employee. Employees of these companies pose as strangers who happen to meet the target, and then become involved in an affair. In 2005, there were around twelve such companies in Japan, but has grown since with companies offering services through the internet.

(via WikiPedia)