  We perform global three-dimensional (3D) radiation-hydrodynamic (RHD)
simulations of out- flow from supercritical accretion flow around a 10 Msun
black hole. We only solve the outflow part, starting from the axisymmetric 2D
simulation data in a nearly steady state but with small perturbations in a
sinusoidal form being added in the azimuthal direction. The mass accretion rate
onto the black hole is ~10^2 L_E/c^2 in the underlying 2D simulation data and
the outflow rate is ~10 L_E/c^2 (with LE and c being the Eddington luminosity
and speed of light, respectively). We first confirm the emergence of clumpy
outflow, which was discovered by the 2D RHD simulations, above the photosphere
located at a few hundreds of Schwarzschild radii (r_S) from the central black
hole. As prominent 3D features we find that the clumps have the shape of a torn
sheet, rather than a cut string, and that they are rotating around the central
black hole with a sub-Keplerian velocity at a distance of ~10^3 r_S from the
center. The typical clump size is ~30 r_S or less in the radial direction, and
is more elongated in the angular directions, ~hundreds of r_S at most. The
sheet separation ranges from 50 to 150 r_S. We expect stochastic time
variations when clumps pass across the line of the sight of a distant observer.
Variation timescales are estimated to be several seconds for a black hole with
mass of ten to several tens of Msun, in rough agreement with the observations
of some ultra-luminous X-ray sources.
