  We explore the neutrino portal dark matter (DM) at its minimum of field
content having two dark sector particles coupled to a right-handed neutrino.
Assuming the feeble nature of their interactions with the standard model (SM)
particles, we analyze the freeze-in production of the observed DM relic density
characterized by three different categories depending on the major production
mechanisms. The portal provides interesting signatures at the neutrino
detectors like KamLAND, Super-Kamiokande and IceCube, from a very late decay of
the scalar DM to the fermion DM and the SM neutrino. Such neutrino flux
spectrum from the cosmic and galactic origins can produce anomalous signals at
future experiments.
