  We propose a three loop radiative neutrino mass scenario with an isolated
doubly charged singlet scalar $k^{\pm\pm}$ without couplings to the charged
leptons, while two other singly charged scalars $h_1^\pm$ and $h_2^\pm$ attach
to them. In this setup, the lepton flavor violation originating from
$k^{\pm\pm}$ exchanges is suppressed and the model is less constrained, where
some couplings can take sizable values. As reported in our previous work, the
loop suppression factor at the three loop level would be too strong and
realized neutrino masses in a three loop scenario could be smaller than the
observed minuscule values. The sizable couplings can help us to enhance
neutrino masses without drastically large scalar trilinear couplings appearing
in a neutrino mass matrix, which tends to drive the vacuum stability to become
jeopardized at the one loop level. Now the doubly charged scalar $k^{\pm\pm}$
has less constraint via lepton flavor violation and the vacuum can be quite
stable, and thus a few hundred GeV mass in $k^{\pm\pm}$ is possible, which is
within the LHC reach and this model can be tested in the near future. Note that
the other $h_1^\pm$ and $h_2^\pm$ should be heavy at least around a few TeV. We
suitably arrange the charges of an additional global $U(1)$ symmetry, where the
decay constant of the associated Nambu-Goldstone boson can be around a TeV
scale consistently. Also, this model is indirectly limited through a global
analysis on results of the LHC Higgs search and issues on a dark matter
candidate, the lightest Majorana neutrino. After $h_1^\pm$ and $h_2^\pm$ are
decoupled, this particle couples to the standard model particles only through
two charge parity even scalars in theory and thus information on this scalar
sector is important. Consistent solutions are found, but a part of them is now
on the edge.
