I present deep ALMA observations for a bright star-forming galaxy at z~7 identified by our wide-area Subaru imaging and Keck spectroscopy. Our supplementary high-resolution HST imaging successfully locates a very blue star-forming core, together with two bright clumps similar to typical L* dropout galaxies. Combining these ALMA and HST results, I discuss properties of dust/metal enrichment of starbursts and gas dynamics at the early epoch of galaxy formation. I also show our recent ground-based NIR spectroscopy to understand chemical and dynamical properties of high-z starburst analog, and to uncover physical origin of strong Lya emission line commonly found at high redshifts. At the end of my presentation, I report progresses of next generation Subaru Hyper Suprime-Cam survey program for galaxies and cosmic reionization.