1 Introduction

2 Data and Sample Selection
2.1 Effective Region in the HSC-Wide Dataset
2.2 Quasar pair sample at z<3.6
2.3 Imaging data and method

3 Result I: z>3 Quasar Pair Environments
3.1 Discovery of proto-clusters at z=3.3 & 3.6
3.2 A faint quasar candidate in the pair fields

4 Quasar Pairs at z~1
4.1 z~1 quasar pair selection
4.2 z~1 single quasars
4.3 z~1 galaxy selection
4.4 Random fields around z~1 galaxies

5 Result II: z~1 Quasar Pair Environments
5.1 Significance distribution
5.2 Significance dependence on redshift

6 Discussion
6.1 Enhancement of overdensity around z>3 quasar pairs
6.2 Redshift dependence of quasar pair environments

7 Summary