Businesses small and large are looking to cash in on the potential for smartphones and wearable devices as health care trends toward the digital age.

They are especially interested in preventive medicine, an area that could ultimately help rapidly graying Japan slash its ballooning medical costs, which topped ¥40 trillion in fiscal 2014.

"Japan's medical spending is reaching its limit ... if there are things that can be streamlined, we need to do it. I think digital health care services can spark such efforts," Masato Iwasaki, a director at Takeda Pharmaceutical Co., said at a recent event for health care startups hosted with Daiichi Sankyo and DeNA Co.