Translation guide
Describes someone who becomes a millionaire very quickly, often through a sudden windfall like a lottery win, inheritance, or business success. Japanese expresses this with compound nouns or descriptive phrases.
He became an overnight millionaire through the lottery.
Means 'a great wealthy person in one night'. Emphasizes the suddenness and magnitude.
The entrepreneur became an overnight millionaire.
Literally 'sudden nouveau riche'. Carries a slightly negative nuance of being newly rich and possibly lacking refinement.
He's an overnight millionaire and suddenly bought a luxury car.
Focusing on the event or state of becoming a millionaire overnight, rather than the person.
Standard phrase: 'to become a millionaire overnight'. Uses 億万長者 (millionaire) and 一夜で (in one night).
He dreams of becoming an overnight millionaire.
More colloquial: 'to become a very rich person overnight'. 大金持ち is a common term for a wealthy person.
一夜富豪 is a neutral term for someone who became rich overnight. 成金 (narikin) means 'nouveau riche' and often implies a lack of class or sudden, perhaps undeserved, wealth. Use 成金 carefully as it can be derogatory.
He dislikes the flashy tastes of the nouveau riche.
Avoid directly translating 'overnight millionaire' word-for-word as オーバーナイト・ミリオネア. While understood by some, it sounds unnatural. Use the Japanese expressions provided.
That investment made him an overnight millionaire.