  We present a global kinetic plasma simulation of an axisymmetric pulsar
magnetosphere with self-consistent $e^\pm$ pair production. We use the
particle-in-cell method and log-spherical coordinates with a grid size
$4096\times 4096$. This allows us to achieve a high voltage induced by the
pulsar rotation and investigate pair creation in a young pulsar far from the
death line. We find the following. (1) The energy release and $e^\pm$ creation
are strongly concentrated in the thin, Y-shaped current sheet, with a peak
localized in a small volume at the Y-point. (2) The Y-point is shifted inward
from the light cylinder by $\sim 15\%$, and "breathes" with a small amplitude.
(3) The dense $e^\pm$ cloud at the Y-point is in ultra-relativistic rotation,
which we call super-rotation, because it exceeds co-rotation with the star. The
cloud receives angular momentum flowing from the star along the poloidal
magnetic lines. (4) Gamma-ray emission peaks at the Y-point and is collimated
in the azimuthal direction, tangent to the Y-point circle. (5) The separatrix
current sheet between the closed magnetosphere and the open magnetic field
lines is sustained by the electron backflow from the Y-point cloud. Its
thickness is self-regulated to marginal charge starvation. (6) Only a small
fraction of dissipation occurs in the separatrix inward of the Y-point. A much
higher power is released in the equatorial plane, especially at the Y-point
where the created dense $e^\pm$ plasma is spun up and intermittently ejected
through the nozzle between the two open magnetic fluxes.
