M. Sato ([27], [28]) introduced a new class of generalized functions, called hyperfunctions, as the n-th derived sheaf of the sheaf of holomorphic functions. He left without proof many details in these papers. To this day, subsequent papers of mathematicians, especially Japanese, completed these "gaps" ([3], [10], [13], [15], [18], [20], [30]). Hyperfunctions have many important properties which are indispensable for an exquisite theory of partial differential equations, microfunctions, micro-local analysis, Fourier transform (cf. [13]). They became a major tool of several areas of analysis and applications.