Born in Hyogo Prefecture in 1958. After graduating from Kyoto University Faculty of Law, Adachi registered as a lawyer (Hiroshima Bar Association) in 1991. His involvement in providing support to atomic bomb survivors living in Korea led him to become involved in numerous atomic bomb-related lawsuits. He is currently the leader of the defense team for the second “Black Rain” lawsuit in Hiroshima, and is also a member of the defense team for the Nagasaki A-bomb survivors' lawsuit. He is co-chair of the Japan NGO Network for Nuclear Weapons Abolition. He is also co-chair of the Hiroshima Alliance for Nuclear Weapons Abolition (HANWA).