Inclusion Criteria:  Participants with unresectable advanced or recurrent gastric cancer (including esophagogastric junction cancer) that has been histologically confirmed to be predominant adenocarcinoma Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) score 0 or 1 Participants who have a life expectancy of at least 3 months  Exclusion Criteria:  Participants with a history or complications of multiple cancers Participants with a complication or history of severe hypersensitivity to any other antibody products Participants with concurrent autoimmune disease or a history of chronic or recurrent autoimmune disease.