[en] This report is the work of six US scientists who surveyed and assessed Japanese research and development in magnetic fusion. All of the panelists are very familiar with Japanese fusion research through their knowledge of the published scientific literature and through personal contacts with Japanese colleagues and with US colleagues who have visited Japanese research facilities. This report concentrates on the period from the early 1980s through June 1989. The technical accomplishments during this period are reviewed, and the Japanese capabilities and outlook for future contributions are assessed. Detailed evaluations are provided in the areas of basic and applied plasma physics, tokamak confinement, alternate confinement approaches, plasma technology, and fusion nuclear technology and materials. With a sustained national commitment, Japan will surpass US and West European capabilities in the early to middle 1990s in several important areas of fusion research and development. For example, it is expected that the planned upgrade of the Japanese JT-60 tokamak will surpass both the US Tokamak Fusion Test Reactor (TFTR) and the Joint European tours (JET) in the usual measures of plasma performance in the 1992 to 1993 timeframe, and will take a clear international lead in large-tokamak research by 1994 to 1995. The Japanese fusion program has the human and technological resources required to build and operate a fusion engineering test reactor without external participation. By the same measure, Japan would be a highly desirable partner in the bilateral undertaking of such a project