Nintendo Co.'s experiment with a built-from-scratch mobile game is off to an underwhelming start.

Dragalia Lost, released last week, is the company's first smartphone title featuring original characters rather than established stars like Super Mario and Donkey Kong. Over its first five days, the game generated $3 million in revenue in the United States and Japan — less than all three of its previous mobile titles — according to a report from researcher Sensor Tower. The early results will be disappointing to investors. After waiting years to embrace mobile gaming, Nintendo has had limited success over the first two years. That prompted a partnership with CyberAgent Inc., a mobile developer known for high profitability, to co-produce Dragalia Lost. For now, the title's reliance on original characters is proving to be a hard sell.

Dragalia Lost ranked 71st by revenue among all iPhone apps in the U.S. as of Oct. 2, down from its debut last week at 61st, according to Sensor Tower. In Japan it is faring better, ranking eighth and up from its debut at 13th.