Black koshirae refers to a coordinated mounting ensemble - tsuka, saya, and fittings - unified under a dark aesthetic. In practice, this means tsuka wrapped in black ito cord over genuine rayskin same, lacquered saya in gloss or matte black, and metal fittings in blackened iron, dark copper, or contrasting gold. The term koshirae distinguishes a fully fitted mounting from a shirasaya, which is a plain wood storage form. For collectors, a coherent black koshirae signals intentional aesthetic design: every component from kojiri to kashira has been selected to complement the blade's geometry and the overall visual presentation of the piece.