A number of familiar criticisms have arisen in Japan around investor-state arbitration (ISA), in particular in relation to the Trans-Pacific Partnership (TPP) negotiations: ISA infringes on state sovereignty; it is unconstitutional; it unduly restricts regulatory space; and it unduly restricts government procurement. But the complete lack of discussion concerning ISA being included in treaties with Switzerland and the Republic of Korea, as well as during the economic partnership agreement negotiations with the European Union, indicates that few people in Japan believe that ISA with developed states is unnecessary or problematic. What makes the TPP appear problematic is the presence of the United States, as it is perceived that Japan may well be brought to arbitration by US investors.