(Proposal ID) S13A-039 (PI) Kodama, Tadayuki (Proposal Title) Scrutinizing the biased galaxy formation in three proto-clusters at z>2 (Abstract) We have completed the imaging part of the Mahalo-Subaru project in which we have mapped out star-forming activities over the wide range in redshift (1.5--2.5) and in environment. Our unique sample of clusters and the narrow- band (NB) emitters therein will serve as excellent laboratories to investigate the environment-dependent galaxy formation. We here propose to conduct near- infrared (NIR) MOIRCS spectroscopy of the 3 most distant proto-clusters in our sample. We will target ~ 141 H alpha emitters in and around the proto-clusters, and detect a series of major nebular emission lines for bright sources in order to fully characterize the properties of the NB emitters. Specifically, we will derive (1) membership of emitters to confirm structures, and velocity dispersion of each clump as a proxy of its system mass, (2) true star formation rates reliably corrected for dust extinction, and nature of the red emitters under the influence of environmental effect, (3) gaseous metallicities to characterize evolutionary states, and (4) AGN contribution to investigate co- activation with SF activity, and compare these quantities in detail as a function of redshift and environment to physically understand the biased galaxy formation at high-z and the rapid decline of star forming activities with time in dense environments.