  Long-term neutrino-radiation hydrodynamics simulations in full general
relativity are performed for rotating massive stars that are evolved from
He-stars with their initial masses of $20$ and $32M_\odot$. It is shown that if
the collapsing stellar core has sufficient angular momentum, the
rotationally-supported proto-neutron star (PNS) survives for seconds
accompanying the formation of a massive torus of mass larger than $1\,M_\odot$.
Subsequent mass accretion onto the central region produces a massive and
compact central object, and eventually enhances the neutrino luminosity beyond
$10^{53}$ erg/s, resulting in a very delayed neutrino-driven explosion in
particular toward the polar direction. The kinetic energy of the explosion can
be appreciably higher than $10^{52}$ erg for a massive progenitor star and
compatible with that of energetic supernovae like broad-line type-Ic
supernovae. By the subsequent accretion, the massive PNS collapses eventually
into a rapidly spinning black hole, which could be a central engine for
gamma-ray bursts if a massive torus surrounds it.
