  Structure of spinning particle based on the rotating black hole solution is
considered. It has gyromagnetic ratio $g=2$ and a nontrivial twistorial and
stringy systems. The mass and spin appear from excitations of the Kerr circular
string, while the Dirac equation describes excitations of an {\it axial}
stringy system which is responsible for scattering. Complex Kerr geometry
contains an open twistor-string, target space of which is equivalent to the
Witten's `diagonal' of the $ CP^3\times CP^{*3}$.
