Using Hyper Suprime-Cam, a gigantic wide-field camera on the Subaru Telescope, astronomers have begun a wide-area survey of the distribution of dark matter in the universe. By accurately measuring the shapes of numerous galaxies in the image, a map of dark matter was determined by weak lens analysis. In 2015, scientists discovered nine large concentrations of dark matter in an area of 2.3 square degrees on the sky toward the constellation Cancer. Surveying how dark matter is distributed and how the distribution changes over time is essential to understanding the role of dark energy that controls the expansion of the universe. Astronomers are now ready to create a 1,000 square degree dark matter map that will reveal the expansion history of the universe with precise detail.