Affiliations from Nov. 2023:
International Center for Hadron Astrophysics, Chiba University
1-33 Yayoi-Cho, Inage-ku, Chiba 263-8522, Japan
Institute for Cosmic Ray Research, University of Tokyo
5-1-5 Kashiwa-no-Ha, Kashiwa, Chiba 277-8582, Japan

View of the Roman aqueduct in Segovia, Spain, July 2019.

Previous toppage photo of Observatorio del Roque de los Muchachos, La Palma, Spain
Old toppage photo of Heidelberg, Germany

Theoretical and Observational Astrophysics
including:
High energy astrophysical processes (Particle acceleration, Radiative processes, Black hole accretion, Jets, ...)
High energy astrophysical objects (Active galactic nuclei, Gamma-ray bursts, Supernovae, Clusters and Structure Formation Shocks, ...)
Nuclear and particle astrophysics (Nucleosynthesis, Cosmic ray and neutrino interactions, ...)
Interface of high energy astrophysics and cosmology
 (High energy nonthermal processes in galaxies, clusters & the intergalactic medium,
  Gamma-ray bursts and active galactic nuclei as probes of cosmology and the high redshift universe,
  Active galactic nuclei evolution and feedback, ...)
Observational studies of high energy and other astrophysical objects
 (Gamma-ray, hard X-ray and radio observations of clusters,
  Optical spectroscopic observations of metal-poor halo stars, ...)
Science with current and future observational facilities
- CTA LST (Large-Sized Telescope) Project and MAGIC: Member of MAGIC+LST Joint Time Allocation Committee (2024-)
- MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov): Convener of Transients Physics Working Group (Jan. 2017 - Mar. 2020)
- CTA (Cherenkov Telescope Array): Coordinator of Transients Science Working Group (Sep. 2016 - Apr. 2017)
  Convener of Extragalactic Science Working Group (Oct. 2013 - Sep. 2016)
  Leader of GRB Physics Working Group (Oct. 2010 - Sep. 2013)
- ASKAP (Australian Square Kilometer Array Pathfinder): Member of EMU (Evolutionary Map of the Universe) Team (Dec. 2019-)
- SKA (Square Kilometer Array): Cosmic Dawn/Epoch of Reionization Team & Cosmology Team (July 2013-)
- JEM-EUSO (Extreme Universe Space Observatory onboard Japanese Experiment Module): Science Objective Working Group Member (Apr. 2006-)