I am studying the properties of one of the elementary particles, neutrino. I am working on an experiment called T2K, in which neutrinos produced by the J-PARC accelerator located in Ibaraki Prefecture are detected by the Super-Kamiokande detector in Gifu Prefecture, about 300 kilometers away. This experiment is investigating whether there is any difference in the behavior of neutrinos and antineutrinos. I am also working on another experiment, called AXEL, to search for the phenomenon of double-beta decay without neutrino emission. This phenomenon occurs if neutrinos and antineutrinos are actually the same particle. In this case, even though they are the same particle, they have different spin directions, i.e., they behave as neutrinos if they spin leftward in the direction of flight, and as antineutrinos if they spin rightward. Neutrinos are really mysterious particles, and their strangeness is considered to be an important key to solving the mysteries of the origin of elementary particles and the beginning of the universe.