Current theories of galaxy formation suggest that large galaxies like the Milky Way grow by consuming smaller dwarf galaxies. Thanks to the wide-field imaging capability at the prime focus, the Subaru Telescope discovered a record-breaking faint dwarf (satellite) galaxy. It also revealed the structure of satellite galaxies and the properties of their stars. Astronomers have obtained a deep panoramic image of the nearby large spiral galaxy M81 and successfully traced the distribution of stars around M81 and its neighbor galaxies. The Subaru Telescope tackles “Galactic Archeology” to understand how large galaxies and their neighbor satellite galaxies form and evolve.