I will talk about our recent discovery of a 22kpc-size extended structure around a supermassive black hole (SMBH) at z=6.4. The structure is likely to be 60% Lyman alpha emission and 40% continuum.This is the first time such an extended emission was found around a SMBH at z>6, and thus, has an important implication for the SMBH/galaxy formation. We also found an overdensity of galaxies by 7 times around the same SMBH. This could be a discovery of the most distant proto-cluster around a SMBH at z=6.4. The galaxies avoid immediate vicinity of the SMBH, possibly suggesting suppression of galaxy formation by strong UV radiation from the SMBH. To confirm this, our recent narrow-band observation found no Lyman alpha emitting galaxies when ~100 are expected. Lastly, we performed the Gunn-Peterson test with the SMBH to measure the cosmic re-ionization history. In the SMBH spectra, we found a 300Mpc-long dark region where flux was consistent with zero. I will present the optical depth measurements, and discuss the implication for the cosmic reionization history.