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.
小姓は、主君に近侍して雑務や日常生活に必要な取り次ぎをすることが主な仕事となっていくが、建て前上の役目の第一は、将軍・藩主などの主君の警護である。