The matter and antimatter asymmetry observed so far in the baryon sector is too small to explain coherently the predominance of matter in our universe with a realistic inflation scenario. I have focused on searching this asymmetry in the lepton sector, through neutrino oscillation at the T2K and Super-Kamiokande experiments. After having observed the appearance of electron neutrinos in a muon neutrino beam, we have recently shown hints that antineutrino may oscillate differently. Through the construction of a new detector to decrease systematic uncertainty and T2K-Super-Kamiokande combined analysis, I aim to provide evidence of this asymmetry.