OSAKA, Japan— Nintendo Co. is set to unveil its first videogame for smartphones on Thursday, a day after weaker-than-expected financial results underscored the company’s need to develop new business to support its struggling console operations.

“We will talk about details tomorrow,” Nintendo’s new chief executive, Tatsumi Kimishima, said Wednesday.

For the first time in five years, Nintendo reported an operating profit for the first half of its fiscal year, as hit game titles helped sales of its game machines. But the earnings fell short of analyst forecasts, reflecting weakening momentum for the company’s Wii U console and 3DS hand-held devices, both of which have been on the market for several years.

For the six months ended in September, Nintendo recorded an operating profit of ¥8.98 billion ($74.6 million), a turnaround from a loss of ¥215 million a year earlier. Analysts had expected an operating profit of ¥14.4 billion. Sales rose to ¥204.2 billion from ¥171.4 billion, but net income fell to ¥11.5 billion from ¥14.3 billion. Last year, Nintendo’s net profit was inflated by gains in the dollar.

Analysts say sales of the Nintendo devices could slow further as stronger rivals, such as Sony Corp.’s PlayStation 4, add peripheral tools to lure more users.