  We study theoretical neutrino signals from core-collapse supernova (CCSN)
computed using axisymmetric CCSN simulations that cover the post-bounce phase
up to $\sim 4$~s. We provide basic quantities of the neutrino signals such as
event rates, energy spectra, and cumulative number of events at some
terrestrial neutrino detectors, and then we discuss some new features in the
late phase that emerge in our models. Contrary to popular beliefs, neutrino
emissions in the late phase are not always quiet, but rather have temporal
fluctuations, the vigor of which hinges on the CCSN model and neutrino flavor.
We find that the temporal variations are not primarily driven by proto-neutron
star (PNS) convection, but by fallback accretion flows in explosion models. We
assess the detectability of these temporal variations, and conclude that
IceCube is the most promising detector with which to resolve them. We also
update fitting formulae first proposed in our previous paper for which total
neutrino energy (TONE) emitted at the CCSN source is estimated from the
cumulative number of events at each detector. This will be very powerful in the
data analysis of real observations, in particular for low-statistics data. As
an interesting demonstration, we apply our fitting formulae to a real
observation, that of SN 1987A at Kamiokande-II. The TONE is estimated as $\sim
2 \times 10^{53}$~erg. By combining the recent constraints on the
equation-of-state, we further estimate the gravitational mass of PNS in the
remnant of SN 1987A, which is $\sim 1.2~M_{\sun}$.
