Since their first discovery in 1995, over a few thousands exoplanets have been spotted so far. Most of them however, have been discovered by indirect observation. In contrast, the Subaru Telescope is exceptional in that it has found exoplanets by direct imaging. In an unprecedented 2013 discovery, researchers successfully located and directly imaged exoplanet GJ 504 b. This exoplanet orbits a Sun-like star GJ 504 at 60 light years from Earth. The mass of this exoplanet was estimated from the star’s luminosity and age, yielding a very reliable mass estimate. GJ 504 b is the least massive, faintest, and coolest exoplanet ever imaged. This discovery marks an important step toward the direct imaging of so-called “second-Jupiter.”