A Study to Demonstrate the Bioequivalence of Lecanemab Supplied in Vials and a Single-Use Auto-Injector (AI) in Healthy Participants

Inclusion Criteria: 1. Non-smoking, male or female, age greater than or equal to (\>=) 18 years and less than or equal to (\<=) 65 years at the time of informed consent. To be considered non-smokers, participants must have discontinued smoking for at least 4 weeks before dosing 2. Body Mass Index \>=18 and less than (\<) 30 kilogram per square meter (kg/m\^2) at Screening Exclusion Criteria: 1. Clinically significant illness that requires medical treatment within 8 weeks of dosing or a clinically significant infection that requires medical treatment within 4 weeks of dosing 2. Evidence of disease that may influence the outcome of the study within 4 weeks before dosing; example, psychiatric disorders and disorders of the gastrointestinal tract, liver, kidney, respiratory system, endocrine system, hematological system, neurological system, or cardiovascular system, or participants who have a congenital abnormality in metabolism 3. Currently enrolled in another clinical study or used any investigational drug or device within 28 days or 5 half-lives of the other investigational drug, whichever is longer, preceding informed consent 4. Prior exposure to lecanemab, or any other anti-amyloid therapies 5. Hypersensitivity to lecanemab or any of the excipients, or to any (monoclonal anti-body \[mAb\]) treatment