Our universe hosts extreme environments such as black holes, active galactic nuclei, and supernova remnants that cannot be reproduced in any terrestrial laboratory. In these regions, particles are accelerated to nearly the speed of light, and intense magnetic fields and radiation fields release enormous amounts of energy. Our laboratory aims to uncover how such extreme phenomena are generated, through a combination of observation and theory. One of our central themes is the physics of phenomena occurring around black holes. In their immediate vicinity, a hot plasma called the corona and relativistic jets launched at near light speed produce emission across the entire electromagnetic spectrum, from radio to gamma rays. Using world-leading facilities such as ALMA and the Fermi satellite, we investigate the magnetic field structures and particle acceleration mechanisms operating around black holes. We also work toward opening up the MeV gamma-ray band, long known as the "MeV gap" due to its observational difficulty, through next-generation missions. In addition, multi-messenger astronomy, which combines light with other cosmic signals such as cosmic rays, neutrinos, and gravitational waves, forms another important approach of our group. Building on this expertise in high-energy astrophysics, we also aim to extend our work to the study of the lunar radiation environment as an applied research direction. Lacking both an atmosphere and a global magnetic field, the Moon is directly exposed to cosmic rays and solar energetic particles, posing a major challenge for crewed lunar exploration. By drawing on our experience in modeling and observing astrophysical phenomena, we aim to provide foundational data that will support future lunar activities. Students take on a wide range of topics, from observational data analysis to theoretical modeling and numerical computation, tailored to their individual interests and aptitudes. Through collaborations with leading institutions in Japan and abroad, we aim to nurture researchers and engineers who will thrive at the forefront of international science.