  Bipolar explosion models for hypernovae (very energetic supernovae),
associated with the black hole formation, are presented. The model features are
as follows: (1) Fe-peak elements are ejected at high velocities to reach the
surface region, while dense O-rich materials occupy the central region at low
velocities. (2) The abundance ratios (Zn, Co)/Fe are enhanced while the ratios
(Mn, Cr)/Fe are suppressed. The overall abundances are consistent with those
observed in extremely metal-poor stars formed at the very early phase of the
Galaxy, suggesting significant contribution of such explosions to the early
Galactic chemical evolution. (3) Certain relations among the optical
luminosity, the chemical composition, and the property of the central remnant
are predicted. Such relations may serve for identifying possible gravitational
wave emitters in the future.
