I am working on a Cosmic Microwave Background (CMB) polarization observation satellite, LiteBIRD mission. With LiteBIRD it is possible to perform a verification of typical inflation models, searching for primordial gravitational waves generated in the early universe through all-sky observation of CMB polarization. The mission is now in the stage of feasibility verification and detector development, aiming to launch in the 2020s. My research focuses on the development of optical system which leads CMB to focal plane detectors. I am challenging an observation of ultrahigh energy physics of the early universe, using my background in particle physics.