The correlation on the distribution between neutral hydrogen intergalactic medium (IGM) and galaxies now attracts great interests. In the MAMMOTH project, Cai+2016 found that Coherently Strong Lyman-alpha Absorption Systems can be ideal tracers for the most massive overdensities. We performed deep narrowband imaging on the 8.2-m Subaru Telescope with Hyper Suprime-Cam to probe the Lyman Alpha Emitters (LAEs) in such most extreme group of HI absorbers, where the effective optical depth over 15 cMpc is 4 to 6 times higher than the mean optical depth at z = 2.2, in the quasar spectra drawn from the complete SDSS-IV/eBOSS database over 10,000 deg^2. The survey volume is one order of magnitude larger than any existing high-z galaxy survey, enabling our discovery of the rarest and most massive systems. This time we will show our results of the massive large scale structures found in the 4 selected fields. And based on such a unique overdensity sample, the latest preliminary results of our global correlation analysis between neutral IGM gas and LAEs at the epoch of Cosmic Noon will be also shown in the workshop.