black tassel hung above the northwest corner of the sumo ring
A specific sumo term referring to one of the four colored tassels suspended above the dohyō; the black tassel is associated with the northwest corner.
土俵の北西の隅には黒房が吊るされている。
A black tassel is hung above the northwest corner of the sumo ring.
Compound of 黒 (black) and 房 (tassel). The term is specific to sumo, where colored tassels mark the corners of the ring.