Hyper-Kamiokande will be a next-generation underground water Cherenkov detector with a total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that of Super-Kamiokande. One of the main goals of Hyper-Kamiokande is the study of asymmetry in the lepton sector using accelerator neutrino and anti-neutrino beams. In this paper, the physics potential of a long-baseline neutrino experiment using the Hyper-Kamiokande detector and a neutrino beam from the J-PARC proton synchrotron is presented. The analysis uses the framework and systematic uncertainties derived from the ongoing T2K experiment. With a total exposure of 7.5 MW s integrated proton beam power (corresponding to protons on target with a 30 GeV proton beam) to a off-axis neutrino beam, it is expected that the leptonic phase can be determined to better than 19 degrees for all possible values of , and violation can be established with a statistical significance of more than ( ) for ( ) of the parameter space. Using both appearance and disappearance data, the expected 1 uncertainty of is 0.015(0.006) for .