  We present the discovery of the simultaneous flux variation of a massive
young stellar object (MYSO) G036.70+00.09 (G036.70) both in the maser emission
and mid-infrared (MIR;$\lambda=3$--$5$~$\mu$m) bands. Utilizing the ALLWISE and
NEOWISE archival databases covering a long time span of approximately 10 years
with a cadence of 6 months, we confirmed that G036.70 indicates a stochastic
year-long MIR variability with no signs of the WISE band color change of W1
(3.4~$\mu$m) $-$W2 (4.6~$\mu$m). Cross-matching the MIR data set with the
high-cadence 6.7~GHz class II methanol maser flux using a Hitachi 32-m radio
telescope that discovered its periodicity in the methanol maser of 53.0--53.2
days, we also determine the flux correlations between the two bands at two
different timescales, year-long and day-long, both of which have never been
reported in MYSOs except when they are in a state of the accretion burst phase.
The results of our study support the scenario that a class II methanol maser is
pumped up by infrared emission from accreting disks of MYSOs. We also discuss
the possible origins of MIR and maser variability. To explain the two observed
phenomena, a stochastic year-long MIR variability with no signs of significant
color change and maser-MIR variability correlation, change in mass accretion
rate and line-of-sight extinction because of nonaxisymmetric dust density
distribution in a rotating accretion disk are possible origins. Observations
through spectroscopic monitoring of accretion-related emission lines are
essential for determining the origin of the observed variability in G036.70.
