expression, i-adjective
still waters run deep
A proverb meaning that a quiet or calm exterior often hides a deep, complex, or passionate nature. Used to describe people who appear reserved but are thoughtful or intense.
彼はあまり話さないけど、静かに流れる川は深いって言うからね。
He doesn't talk much, but they say still waters run deep.
A Japanese proverb equivalent to the English 'still waters run deep'. The exact origin is uncertain, but it is a traditional saying.