The Japanese Garden, dedicated in 1977, was designed by the late Professor Koichi Kawana, a native of Japan and lecturer on environmental design and landscape architecture at the University of California, Los Angeles. 

Rather than the typical garden filled with striking statuary, showy plants and flowers, the Japanese Garden is a monochromatic understatement, in which the viewer is permitted the thrill of personal interpretation and discovery. Such gardens, with a lake as their main feature, were popular among the Japanese feudal lords or daimyo of the 17th and 18th centuries. Because of the extensive lawn areas, they possess a feeling of openness unique to this style. The Japanese Garden also includes various garden styles that were developed by the Japanese in prior centuries.

Great care was taken with Seiwa-en to ensure that the Garden would be traditionally authentic, incorporating in its design many concepts that make a garden more than greenery. The visitor to Seiwa-en will see distinct aspects of its beauty when viewing it from different vantage points. It is a world in microcosm, featuring carefully designed waterfalls, beaches and islands, sometimes with minimal plantings, as in the raked dry gravel gardens.