non-linear physics. During this period, one visiting professor position was created to invite distinguished foreign physicists. Unification with the RITP in Hiroshima (1990) The new English name, the Yukawa Institute for Theoretical Physics, was adopted after the unification of two institutions: the Research Institute for Theoretical Physics (RITP) of Hiroshima University and Research Institute for Fundamental Physics (RIFP). RITP of Hiroshima University was founded in 1944 by Yoshitaka Mimura for the research of mathematical foundations of theoretical physics. On August 6, 1945, it lost two faculty members and a supporting staff, together with all its facilities, by the blast of the atomic bomb exploded over Hiroshima. RITP was re-established in 1948 in Takehara, a quiet suburban town of Hiroshima near the water, and stayed there until it was dissolved by the unification in 1990. A major expansion of the institute took place in 1990 when Research Institute for Fundamental Physics (RIFP) was joined by all academic staff members of the Research Institute for Theoretical Physics (RITP) of Hiroshima University. At the time of the unification, RITP had ten academic staff and its research area had expanded to include cosmology, general relativity, field theory, and particle theory. Present YITP By the expansion of 1990, the size of the institute almost doubled in terms of the number of its own academic staffs. Unfortunately Yukawa Hall had no extra office or library space to accommodate the new members of the institute and the library assets from RITP. Temporary settings for new offices and library was arranged in the Uji campus of Kyoto University which is located about 20 km south of Yukawa Hall. Thus, Yukawa Institute became distributed over two distantly located buildings, Yukawa Hall on the Kitashirakawa campus and the Uji Research Center on the Uji campus. In 1995, the completion of the new building of the Yukawa Institute, constructed next to Yukawa Hall, ended this inconvenient situation of having two geographically separated facilities of the institute. The Uji Research Center was closed at this time. The new building now houses the offices of all 22 academic staffs as well as those for visitors, postdoctoral fellows, students and supporting staffs in addition to the new large library and computing facilities. Yukawa Hall is still used for research conferences and workshops organized by the Yukawa Institute besides use for its administrative offices, including Director's, and for the editorial office of the Progress of