One recent Saturday afternoon in Shanghai, a 10-year-old girl – glasses perched on her nose, her pink T-shirt tucked into a purple skirt – led her parents into a Little Genius store. Returning to school after the summer break, she was eager for a new smartwatch and had only one brand in mind.“We checked out Huawei and Xiaomi, but my daughter insisted on getting Little Genius,” the mother told the sales staff.Known locally as Xiaotiancai and abroad as Imoo, Little Genius may be unfamiliar to...