Distribution of HSC stellar objects with spectroscopic information on g − r vs. r − z color–color diagram. Left: Distributions of Galactic stars. Red dots represent Galactic stars; large red open circles represent HSC colors of Galactic stars identified in the z ∼ 4 quasar survey in the COSMOS region (Ikeda et al. 2011). Right: Distributions of extragalactic objects at five different redshift ranges: 0.5 < z < 2.5 (green dots), 2.5 < z < 3.5 (blue crosses), 3.5 < z < 4.0 (pink open circles), 4.0 < z < 4.5 (cyan open squares), 4.5 < z (black triangles). Red solid lines in both of the panels indicate the color selection criteria used in this paper. (Color online)