  We report results from a series of three-dimensional (3D) rotational
core-collapse simulations for $11.2$ and 27 $M_{/odot}$ stars employing
neutrino transport scheme by the isotropic diffusion source approximation. By
changing the initial strength of rotation systematically, we find a
rotation-assisted explosion for the 27$M_{/odot}$ progenitor, which fails in
the absence of rotation. The unique feature was not captured in previous
two-dimensional (2D) self-consistent rotating models because the growing
non-axisymmetric instabilities play a key role. In the rapidly rotating case,
strong spiral flows generated by the so-called low $T/|W|$ instability enhance
the energy transport from the proto-neutron star (PNS) to the gain region,
which makes the shock expansion more energetic. The explosion occurs more
strongly in the direction perpendicular to the rotational axis, which is
different from previous 2D predictions.
