noun
tough exterior, soft heart
Describes a person who appears stern or unyielding but is actually kind and gentle inside. A yojijukugo often used in character descriptions.
彼は内柔外剛な人で、厳しいことを言っても本当は優しい。
He is tough on the outside but soft at heart; even when he says harsh things, he is actually kind.
The opposite: appearing gentle but being tough inside. 内柔外剛 is the reverse, with a hard exterior and soft interior.
A yojijukugo composed of 内 (inside), 柔 (soft), 外 (outside), and 剛 (hard). The exact origin is uncertain, but it follows a common four-character pattern contrasting inner and outer qualities.