T2K (Tokai to Kamioka) is a long-baseline neutrino oscillation experiment with a high-intensity beam of muon neutrinos or muon anti-neutrinos produced at the Japan Proton Accelerator Research Complex (J-PARC). A near detector complex 280 m away from the neutrino source provides information about the un-oscillated neutrino flux and interaction cross-sections. The Super-Kamiokande underground water Cherenkov detector, 295 km away, serves as the far detector and measures the oscillated neutrino flux. The T2K experiment conclusively observed electron neutrino appearance in the muon neutrino beam and provided a precise measurement of muon neutrino dissappearance. T2K started taking data using the muon anti-neutrino beam during the summer of 2014 and its first measurement of muon anti-neutrino disappearance has been already released. Hyper-Kamiokande will be a next generation underground water Cherenkov detector with a total (fiducial) mass of 0.99 (0.56) million metric tons, which is about 20 (25) times larger than that of Super-Kamiokande. Together with the upgraded J-PARC neutrino beam, it will be able to study the CP asymmetry in the lepton sector. In this talk, a review of the results on the neutrino oscillation mixing parameters obtained by T2K and the expected sensitivity of Hyper-Kamiokande will be presented.