Prof. Hosoya studied for his undergraduate degree at Rikkyo University and went on to Birmingham University, where he gained his master’s degree (Master of International Studies) in 1996. At Keio University, he completed his master’s degree in 1997 and PhD in Law in 2000. After time spent as a visiting fellow at Princeton University and Sciences-Po, Paris, he returned to Keio University as a professor in 2010. He held positions as a consultant to the second Abe administration as part of the Council on National Security and Defense Capabilities and an advisor at Japan’s National Security Secretariat.