  We introduce three right-handed neutrinos and three sterile neutrinos, and
consider an inverse seesaw mechanism for neutrino mass generation. From
naturalness point of view, their Majorana masses should be small, while it
induces a large neutrino Yukawa coupling. Then, a neutrinoless double beta
decay rate can be enhanced, and a sizable Higgs mass correction is inevitable.
We find that the enhancement rate can be more than ten times compared with a
standard prediction from light neutrino contribution alone, and an analytic
form of heavy neutrino contributions to the Higgs mass correction. In addition,
we numerically analyze the model, and find almost all parameter space of the
model can be complementarily searched by future experiments of neutrinoless
double beta decay and $\mu \to e$ conversion.
