In January 2011 the international conference ``Differential Geometry and Tanaka Theory--Differential System and Hypersurface Theory'' was held at the Research Institute for Mathematical Sciences (RIMS), Kyoto University, in honor of the sixtieth birthdays of Reiko Miyaoka and Keizo Yamaguchi.

This volume is dedicated to the two professors. The volume contains one survey article and six research articles contributed by international researchers.