  We propose a hidden gauged $U(1)_H$ $Z'$ model to explain deviations from the
Standard Model (SM) values in lepton flavor universality known as $R_K$ and
$R_D$ anomalies. The $Z'$ only interacts with the SM fermions via their mixing
with vector-like doublet fermions after the $U(1)_H$ symmetry breaking, which
leads to $b \to s \mu\mu$ transition through the $Z^{\prime}$ at tree level.
Moreover, introducing an additional mediator, inert-Higgs doublet, yields $b\to
c \tau \nu$ process via charged scalar contribution at tree level. Using flavio
package, we scrutinize adequate sizes of the relevant Wilson coefficients to
these two processes by taking various flavor observables into account. It is
found that significant mixing between the vector-like and the second generation
leptons is needed for the $R_K$ anomaly. A possible explanation of the $R_D$
anomaly can also be simultaneously addressed in a motivated situation, where a
single scalar operator plays a dominant role, by the successful model
parameters for the $R_K$ anomaly.
