The main objective of the study is to assess the relative bioavailability of KAI-9531 subcutaneous (SC) injection in the upper arm and thigh compared to the abdomen.

Inclusion Criteria:

• Body mass index (BMI) ≥ 25.0 and ≤ 40.0 kilograms per square meter (kg/m^2), with a body weight ≤ 120 kg.
• Medically healthy.

Exclusion Criteria:

• Known hypersensitivity to the study drug or any of the study drug ingredients.
• History or presence of clinically significant cardiovascular, pulmonary, hepatic, renal, hematological, gastrointestinal, endocrine, immunologic, dermatologic, psychiatric, or neurological disease/disorder.
• Any history of malignant disease in the last 10 years (excludes surgically resected skin squamous cell or basal cell carcinoma).
• Estimated glomerular filtration rate (eGFR) <60 milliliters per minute per 1.73 square meters of body surface area (mL/min/1.73 m^2) using the 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.
• Glycosylated hemoglobin (HbA1c) test result ≥6.5%.
• A history of or positive test results at the Screening visit for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg) or hepatitis C virus (HCV) antibody (HCVab) with HCV ribonucleic acid (RNA) confirmation if positive.
• Positive drugs of abuse or alcohol test results.
• Participation in another clinical study of an investigational drug or investigational device within 30 days or 5 half-lives of the investigational drug (whichever is longer).
• Any other condition or prior therapy that would make the participant unsuitable for this study, including inability to cooperate fully with the requirements of the study protocol or likelihood of noncompliance with any study requirements.

Note: Additional inclusion/exclusion criteria may apply, per protocol.