Koji received a PhD in physiology from the University of Tokyo School of Medicine under the supervision of Dr. Yasushi Miyashita in 2006. He then worked for Psychology Department at Washington University in St. Louis with Dr. Todd S Braver as a post-doctoral researcher. He moved to Imaging Research Center at the University of Texas at Austin to work with Dr. Russell A Poldrack as a post-doc. He then became an associate professor at Keio University Department of Biosciences and Informatics working as a principal investigator. In September 2022, he joined Gunma University.