Understanding the properties of distant protogalaxies is crucial for constraining the
formation history of present-day cluster galaxies. Although many studies have addressed
the impact of the local environment on galaxy formation and evolution, the role of the
environment at high redshift remains poorly understood. To address this, we conducted
narrow-band imaging with the Subaru Telescope and the JWST for three protoclusters at z
= 2, investigating the properties of star-forming galaxies residing within
them. Notably, in the Spiderweb and USS1558 protoclusters—where the imaging reached
unprecedented depth—we found a significant population of low-mass galaxies undergoing
explosive star formation. This is likely due to frequent galaxy interactions and
mergers, as well as the efficient supply of cold gas from the cosmic web within these
protoclusters. Furthermore, we study the unique filamentary protocluster HS1700 at
z=2.30 using three narrow-band filters targeting Lyα, Hα, and [OIII]
emission. Interestingly, Lyα emitters tend to avoid the high-density regions and the
filament. This behavior is likely caused by resonant scattering of Lyα photons by HI
gas and/or their dust attenuation of member galaxies. Additionally, star-forming
galaxies located on the filament and in the cluster center are found to be more massive
than those in other regions, suggesting that these galaxies have been able to
efficiently acquire gas, leading to accelerated evolution.