expression, godan verb (-ru)
stand tall and intimidatingly; strike a daunting pose
Describes standing with feet apart and arms crossed or akimbo, like a temple guardian statue (仁王), conveying authority or intimidation.
彼は怒って仁王立ちになった。
He stood tall and intimidatingly in anger.
門の前に仁王立ちになって通行
He stood in a daunting pose in front of the gate and glared at passersby.