アブストラクト：
We will present the results of our Lyman alpha imaging around a hyperluminous QSO, HS1549+1919, at z=2.84 with Hyper Suprime-Cam (HSC) on the Subaru telescope. Thanks to the HSC’s overwhelmingly large FoV, we detected >3000 Lyman emitters (LAEs) in diverse environments within a 1.1 deg^2 FoV. The QSO is confirmed to reside in the very center of a protocluster and is surrounded by a ~1pMpc-scale diffuse Lyman alpha nebula. Various properties of LAEs are studied as a function of environments. After sharing the current status, I present our future plans to further reveal galaxy formation in this rich environment, including ongoing multi-wavelength surveys in the field.