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.
小姓は、物理的に主君に最も近い位置で奉公し、その警護と、枢機に預かったため、小姓に任じられた者は、親族を含む他家との交際を禁止する藩もあった。