  Magnetic-field effect on the magnetic and electric properties in a chiral
polar ordered corundum Ni$_2$InSbO$_6$ has been investigated. Single-crystal
soft x-ray and neutron diffraction measurements confirm long-wavelength
magnetic modulation. The modulation direction tends to align along the magnetic
field applied perpendicular to the polar axis, suggesting that the nearly
proper-screw type helicoid should be formed below 77\,K. The application of a
high magnetic field causes a metamagnetic transition. In a magnetic field
applied perpendicular to the polar axis, a helix-to-canted antiferromagnetic
transition takes place through the intermediate soliton lattice type state. On
the other hand, a magnetic field applied along the polar axis induces a
first-order metamagnetic transition. These metamagnetic transitions accompany a
change in the electric polarization along the polar axis.
