This study describes an original view of the expected process intensification (PI) and a methodology for its realization by comparing the present state and trends of PI in the United Kingdom, Europe and USA with those in Japan. It is presently thought that PI should be a model-based process design strategy involving technological innovation at the core of green process engineering (GPE) with the aim of a quantum leap. On the other hand, a clear concept of PI is yet to emerge in Japan, and while it is sometimes interpreted in the above manner, the meaning of model-based is a little different. In particular, constructive design techniques based on phenomenalistic models are regarded as important, through which a quantum leap may be expected to emerge. For the expected PI technology, the systematic integration of process systems, namely compactification, is important, and this will result in complicated systems incorporating many precise elements. This will require a complicated system design strategy that surveys, in order, material design, device design and process design, in which one of the essential problems will be multi-scale modeling-simulation of dynamic complicated systems. In sum, the expected PI will involve design and development strategies for process technology that integrate new model-based unit operations based on various phenomenalistic models represented by the transport phenomena theory. A remaining problem will be further development of precise, efficient and flexible modeling-simulation techniques of complicated systems.