  Cosmic reionization is known to be a major phase transition of the gas in the
Universe. Since astronomical objects formed in the early Universe, such as the
first stars, galaxies and black holes, are expected to have caused cosmic
reionization, the formation history and properties of such objects are closely
related to the reionization process. In spite of the importance of exploring
reionization, our understandings regarding reionization is not sufficient yet.
Square Kilometre Array (SKA) is a next-generation large telescope that will be
operated in the next decade. Although several programs of next-generation
telescopes are currently scheduled, the SKA will be the unique telescope with a
potential to directly observe neutral hydrogen up to z~30, and provide us with
valuable information on the Cosmic Dawn (CD) and the Epoch of Reionization
(EoR). The early science with the SKA will start in a few years; it is thus the
time for us to elaborate a strategy for CD/EoR Science with the SKA. The
purpose of this document is to introduce Japanese scientific interests in the
SKA project and to report results of our investigation.
