The Kyoto-based company earned JPY 14.3 billion between April and September, way up from JPY 600 million in the same period a year ago, despite sales falling 12.8 percent to JPY 171.4 billion on lacklustre demand for its 3DS games system.
Nintendo kept its full-year JPY 20 billion profit forecast unchanged, and said its operating loss in the first half shrank to JPY 215 million, from JPY 23.3 billion a year earlier.
The maker of the Super Mario and Pokemon franchises has struggled in recent years, as consumers flee to downloadable games for smartphones and other mobile devices.
Net profit soared "as a result of exchange gains totalling JPY 15.5 billion due to depreciation of the yen", the company said.
A weaker yen helps make Japanese exporters more competitive overseas and inflates the value of their repatriated profits.