Ten years passed since Japan set out the Action Plan of Growth Strategy that declared the initiatives of digitalization for medicine, nursing care, and healthcare to achieve the world’s most advanced medical care. The initiatives formed the foundation of the Japanese national strategy and have been continuously refined, resulting in the current environment of digital health and digital medicine. Digital health–related terminologies are organized, such as “digital health,” “digital medicine,” and “digital therapeutics” (DTx), as well as several common digital technologies, including artificial intelligence, machine learning, and mobile health (mHealth). DTx is included in mHealth and is a novel disease treatment option. Also, this article thoroughly describes DTx in Japan and compares it with those in the US and Germany, the leading countries in digital health–related policies, regulations, and their development status. In Japan, two of three DTx applications that have been approved and reimbursed by the Ministry of Health, Labor, and Welfare are explained in detail in relation to cardiovascular medicine. When added to a standard smoking cessation program, the DTx system for nicotine dependence significantly improved the continuous abstinence rate. Moreover, the DTx for hypertension together with the guideline-based hypertension management was effective in patients aged 65 years or younger who were diagnosed with essential hypertension without antihypertensive agents, and it was also found to be cost-effective. DTx in cardiovascular medicine, with consideration on safety, efficacy, and cost-effectiveness, could be widely used not only through basic experiments and clinical studies but also through social implementation.