  We study the environment of the z=6.33 ultraluminous quasar SDSS
J010013.02+280225.8 (J0100) to understand its association with large-scale
structure. Theoretical models propose high-redshift quasars as markers of
galaxy overdensities residing in the most massive dark matter halos (DMHs) in
the early universe. J0100 is an ultraluminous quasar with the most massive
black hole known at z>6, suggesting a high likelihood of residing in a massive
DMH. We present wide-field ($\sim$522 square arcminute) imaging in the r-, i-,
and z-bands from the Large Binocular Camera on the Large Binocular Telescope,
with Y- and J-band imaging from the Wide-field Infrared Camera on the
Canada-France-Hawaii Telescope, centered on J0100. Applying color selections,
we identify 23 objects as i-droput Lyman Break Galaxy (LBG) candidates in the
J0100 field. We use the deep photometric catalog in the 1.27 square degree
COSMOS field to calculate the density of LBGs in a blank field, and to estimate
the selection completeness and purity. The observed surface density of LBG
candidates in the J0100 field corresponds to a galaxy overdensity of $\delta$=4
(at 8.4$\sigma$). This large-scale overdensity suggests that the $\sim$ 22
square arcminute overdensity found by Kashino et al. using JWST data extends
out to much larger scales. We calculate the angular auto-correlation function
of the candidates and find a positive correlation on $\lesssim$ 10 arcminute
scales as well as evidence of asymmetries in their spatial distribution,
further suggesting a direct detection of large-scale structure around the
ultra-luminous quasar J0100.
