  We study an extension of the scotogenic model with a real singlet scalar. It
gives an origin of the mass of right-handed neutrinos and plays a role of
inflaton through a non-minimal coupling with Ricci scalar. While an inert
doublet scalar is an indispensable ingredient for neutrino mass generation in
the model, it is also a promising dark matter (DM) candidate. Introduction of
the singlet scalar could affect its nature of DM if mass of the singlet scalar
is in a resonance region. We focus our study on such a case where inflaton mass
is expected to be in a TeV range and reheating temperature is less than $10^9$
GeV. Thus the model requires low scale leptogenesis. After examining several
effects brought about by the singlet scalar for the DM sector, we discuss DM
phenomenology such as high energy neutrinos and monochromatic gammas caused by
its annihilation.
