slave-driver manager; heartless section chief
Colloquial, often half-joking term for a strict, demanding, or unsympathetic boss. The 鬼 (oni) prefix intensifies the harshness.
Our slave-driver manager gets angry the moment you refuse overtime.
All the new employees are scared of that heartless section chief.
Compound of 鬼 (oni, 'demon') and 課長 (kachō, 'section chief'). The prefix 鬼- is used figuratively to mean 'fierce' or 'heartless'.