We, at the International Center for Elementary Particle Physics (ICEPP), the University of Tokyo, study the most fundamental particles and forces of nature by using the world's most forefront particle accelerators. At LHC (Large Hadron Collider), at the European Organization for Nuclear Research (CERN), we join the ATLAS experiment to explore Higgs particles and new physics phenomena such as supersymmetry. The MEG experiment at the Paul Scherrer Institut (PSI) looks for definite clues for supersymmetric grand unification of forces and the mystery of tiny neutrino masses by searching for muon's forbidden decays. To further develop these studies in the future we are also working in the world wide efforts to realize the International Linear Collider (ILC).