expression, noun
the cauldron of Hell
Buddhist term referring to the cauldron in Hell where sinners are boiled. Often used in the set phrase 地獄の釜の蓋も開く, meaning even Hell's cauldron lid opens (i.e., even the most unlikely things can happen).
地獄の釜の蓋も開くというから、彼が遅刻しない日もあるかもしれない。
They say even the lid of Hell's cauldron opens, so maybe there will be a day when he isn't late.