Hyper-Kamiokande (HyperK) is a water Cherenkov neutrino detector in Japan with a fiducial mass of 187kton, eight times larger than the Super-Kamiokande. Upgraded J-PARC accelerator located 295km away will provide high intensity of neutrino and anti-neutrino beams tuned at the oscillation maximum. The statistical precision of HyperK will reach 3% for both neutrinos and anti-neutrinos, making sensitive measurement of the leptonic CP violation. Atmospheric neutrinos, where as many as 20k events/year expected, will provide complementary neutrino oscillation studies with very long baseline up to the size of the earth, corresponding to several oscillation maxima. Higher energy atmospheric neutrinos are sensitive to neutrino mass hierarchy through matter resonance effect and tau neutrino appearance. Careful control of systematic uncertainties is essential to exploit the high statistical precision. HyperK uses an intermediate water Cherenkov detector (IWCD) covering wide range of angles to precisely cancel the systematic uncertainties in the neutrino cross section. In this talk, I will describe the challenges of the systematic uncertainties in the future neutrino oscillation experiments and how the HyperK will be able to address them.