  We consider the dark matter model with radiative neutrino mass generation
where the Standard Model is extended with three right-handed singlet neutrinos
($N_1$, $N_2$ and $N_3$) and one additional SU(2)$_L$ doublet scalar $\eta$.
One of the right-handed neutrinos ($N_1$), being lightest among them, is a
leptophilic fermionic dark matter candidate whose stability is ensured by the
imposed $\mathbb{Z}_2$ symmetry on this model. The second lightest right-handed
neutrino ($N_2$) is assumed to be nearly degenerated with the lightest one
enhancing the co-annihilation between them. The effective interaction term
among the lightest, second lightest right-handed neutrinos and photon
containing transition magnetic moment is responsible for the decay of heavier
right-handed neutrino to the lightest one and a photon ($N_2\to N_1 + \gamma$).
This radiative decay of heavier right-handed neutrino %to the the lightest one
with charged scalar and leptons in internal lines could explain the X-ray line
signal $\sim$ $3.5$ keV recently claimed by XMM-Newton X-ray observatory from
different galaxy clusters and Andromeda galaxy (M31). The value of the
transition magnetic moment is computed and found to be several orders of
magnitude below the current reach of various direct dark matter searches. The
other parameter space in this framework in the light of the observed signal is
further investigated.
