inflexible people; heartless people
Idiomatic expression literally meaning 'wooden Buddha, metal Buddha, stone Buddha', used to describe people who are unfeeling, rigid, or lack human warmth.
That boss is as cold as a wooden, metal, or stone Buddha.
The expression is a compound of 木仏 (wooden Buddha), 金仏 (metal Buddha), and 石仏 (stone Buddha), figuratively referring to people who are as unfeeling and rigid as inanimate Buddhist images. The exact origin is uncertain.