The main purpose of the study is to investigate the upper gastro-intestinal (GI)-related safety and tolerability in healthy participants by gastroscopy and gastric biopsies after treatment with 25 milligram (mg) JNJ-67953964 once daily (QD) over 4 weeks.

Inclusion Criteria:

• Body Mass Index (BMI) between 18 and 30 kilograms per meter square (kg/m^2). Minimum body weight should be 50 kilogram (kg)
• Healthy on the basis of clinical laboratory tests performed at screening. If the results of the serum chemistry panel, hematology, or urinalysis are outside the normal reference ranges, the participant may be included only if the investigator judges the abnormalities or deviations from normal to be not clinically significant or to be appropriate and reasonable for the population under study. This determination must be recorded in the participant's source documents and initialed by the investigator
• Non-smokers (not smoked for 3 months prior to screening)
• A woman of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test before the first dose
• A male participant must wear a condom when engaging in any activity that allows for passage of ejaculate to another person until 90 days after receiving the last dose of study intervention

Exclusion Criteria:

• History of malignancy within 5 years before screening (exceptions are squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix, or malignancy, which is considered cured with minimal risk of recurrence)
• History of any gastric surgery, documented gastric disease (including peptic ulcer disease, gastritis, achlorhydria, upper gastro-intestinal (GI) bleeding, esophagitis, or any GI precancerous condition), current clinically evident GI complaints including functional gastrointestinal disorders (FGID)
• Is positive for helicobacter (H.) pylori antigen in a stool test at screening
• Is diagnosed to have any gastric disease (macroscopic) as visually assessed by gastroscopy at screening
• History of human immunodeficiency virus (HIV) antibody positive, or tests positive for HIV at screening

The data sharing policy of the Janssen Pharmaceutical Companies of Johnson & Johnson is available at www.janssen.com/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu