Nyubachibo (literally, mortar [a bowl-shaped vessel] bonze) is one of Japanese yokai (ghosts, spirits and monsters) that was transmuted from a copper disk (cymbal) used as a musical instrument for theatrical performance.
乳鉢坊（にゅうばちぼう）とは、芝居の鳴り物に使う銅盤が変化して生まれた日本の妖怪である。