This report reviews the status of Japanese high-density data storage technology, manufacturing and R&D in comparison to that in the United States. It covers various optical data storage technologies, magnetic hard disk drives, and magnetic tape drives, as well as the emerging long-term data storage technology alternatives. Information sources used in the study include literature review, site visits in Japan, and a review of the draft report by panelists, site visit hosts, and study sponsors. It also includes information obtained from presentations from U.S. panelists and Japanese counterparts given at a workshop that took place in Tokyo prior to the site visits. The organizations chosen for site visits were those that have established a leadership role in some important aspect of data storage technology. In all, the panelists visited 15 Japanese institutions including 5 companies and one government organization involved in optical data storage only, 4 companies focused on magnetic data storage only, and 5 companies that are heavily involved in both magnetic and optical data storage. The panel found that Japan clearly leads in optical data storage and magnetic tape drives, both countries are competitive in magnetic hard disk drives, and researchers in both countries are clearly aware of future challenges in data storage technologies for the next decade. Both the United States and Japan put significant emphasis on long-range alternative data storage techniques. There are clear possibilities for Japan to surpass the United States in the hard disk drive segment and opportunities for the United States to catch up in optical data storage. Japanese government funding in data storage in general appears to far outstrip comparable government funding in the United States. In optical data storage, with Japan being in a comfortable leading position, most R&D funding is derived from industrial sources, although new large government programs in this area are being started. However, there is substantial present government and industrial support for R&D in magnetic hard disk drives where Japan trails the United States.