Experts from Plattform Industrie 4.0/SCI 4.0 (Germany) and the Robot Revolution and Industrial IoT Initiative (RRI, Japan) have worked jointly on smart manufacturing and its standardization. They aim to implement a sustainable society and industry by reducing environmental impact and improving Quality of Life (QoL), which are urgent issues for both countries. Visualization and modelling of products and activities, considering the entire life cycle of artifacts, are important to improve sustainability. The digital twin is the basis for this modelling. The interoperability of digital twins also creates various new possibilities. Based on the ana[1]lysis of use cases in both countries, this paper discusses a reference model of a digital twin and requirements for standardization, with a view to smart manufacturing and its wider application in society.