Volumetric three-dimensional visualization of the nickel distribution for models W15-1, W15-2, L15-1, and L15-2 at the postbounce time given in the top left corner of each panel along with the model name. The semi-transparent isosurfaces correspond to a chosen value of the nickel mass per grid cell of 3 × 10²⁶ g and are displayed at a stage well after all nucleosynthesis processes have seized in our simulations. The orange vectors represent the NS kick directions and are scaled by the corresponding NS velocities (96 km s^-1 for the shortest arrow and 575 km s^-1 for the longest one). The high-kick models W15-1 and W15-2 in the upper two panels exhibit a clear asymmetry with much more nickel being ejected in the hemisphere opposite to the kick direction. In contrast, the moderate-kick models L15-1 and L15-2 in the lower two panels exhibit a more isotropic distribution of the nickel, in particular no obvious hemispheric asymmetry between kick and anti-kick directions. While the radial distribution of the nickel may be strongly affected and changed by subsequent mixing instabilities that develop after the outgoing shock has passed the composition-shell interfaces of the progenitor star, the hemispheric differences in the nickel ejection will not be destroyed during the later supernova explosion.