  SuperKEKB is an electron-positron asymmetric-energy collider to search new
physics phenomena appeared in B-meson decays. In order to accomplish this
purpose, 40 times the luminosity as high as the KEKB collider is demanded. The
strategy is that the vertical beta function at the IP is squeezed down to 1/20
and the beam currents double those of KEKB while keeping the same beam-beam
parameter. The vertical beta function at the interaction point(IP) will be much
smaller than the bunch length, however, the hourglass effect which degrades the
luminosity will be reduced by adopting a novel "nano-beam" scheme. First of
all, the Phase 2 commissioning was focused on the verification of nano-beam
scheme. Secondary, beam related background at the Belle II detector was also
studied for the preparation of the pixel vertex detector installed before the
Phase 3 operation. The preliminary results and accomplishments of the
commissioning in Phase 2 will be reported in this article.
