Jin Koda’s primary interest is the evolution of galactic disks and star formation. Galaxies are concentrations of more than billions of stars, gas, and dust in the Universe, and galactic disks are thin, circular distributions of stars, gas, and dust in the galaxies. Recently, by scouring archival data captured by the Subaru Telescope, he and his collaborators discovered 854 “ultra-dark galaxies” in the Coma Cluster, a region in deep space 330 million light-years from Earth. These galaxies have an unusual amount of dark matter, which is one of the unresolved mysteries of the origin and development of the universe.