The senmin (humble or lowly people) class was divided into five ranks, namely, ryoko (imperial tomb guards), kanko (slaves to public ministries), kenin (slaves of nobles), kunuhi (government-owned slaves), and shinuhi (privately-owned slaves), and the ranks were segregated by a tojikikon system where marriage must be between those of the same class.
賤民の身分は、陵戸、官戸、家人古代の家人（けにん）、公奴婢（ぬひ）、私奴婢の5階層に区別され、各階層は同一身分内部で婚姻しなければならないという当色婚の制度によって隔離されていた。