  We report on simultaneous optical and X-ray observations of the dwarf nova SS
Cyg with Tomo-e Gozen/1.05 m Kiso Schmidt and Neutron star Interior Composition
ExploreR (it NICER) / International Space Station (ISS). A total of four
observations were carried out in the quiescent state and highly correlated
light variations between the two wavelengths were detected. We have extracted
local brightness peaks in the light curves with a binning interval of 1 sec,
called `shots', and have evaluated time lags between the optical and X-ray
variations by using a cross-correlation function. Some shots exhibit
significant optical lags to X-ray variations and most of them are positive
ranging from $+$0.26 to 3.11 sec, which have never been detected.
  They may be ascribable to X-ray reprocessing in the accretion disk and/or the
secondary star. This analysis is possible thanks to the high timing accuracy
and the high throughput of NICER and the matching capability of Tomo-e Gozen.
Also, it is confirmed that the correlation between the optical and X-ray
variations changed in the middle of one of our observation windows and the
X-ray spectrum softer than 2 keV varied in accordance with the correlation.
