The purpose of this study is to demonstrate dose strength equivalence of 2 × 164.4 milligrams (mg) centanafadine (CTN) once daily (QD) extended-release (XR) capsules to a 1 × 328.8 mg centanafadine QD XR capsule in healthy adult participants.

Inclusion Criteria

1. Body mass index (BMI) between 19.0 to 32.0 kilograms per square meter (kg/m^2) (inclusive).

2. In good health as determined by:

   1. Medical history
   2. Physical examination
   3. Electrocardiogram (ECG)
   4. Serum/urine chemistry, hematology, and serology tests.

3. Ability to provide written, informed consent prior to initiation of any trial-related procedures, and ability, in the opinion of the principal investigator, to comply with all the requirements of the trial.

Exclusion Criteria

1. Clinically significant abnormality in past medical history, or at the screening physical examination, that in the investigators or sponsor's opinion may place the participant at risk or interfere with outcome variables including absorption, distribution, metabolism, and excretion of drug.
2. History of drug and/or alcohol abuse within 2 years prior to screening.
3. History of or current hepatitis or acquired immunodeficiency syndrome (AIDS) or carriers of hepatitis B surface antigen (HBsAg) and/or hepatitis C antibodies (anti-HCV), or human immunodeficiency virus (HIV) antibodies.
4. History of any significant drug allergy or known or suspected hypersensitivity.
5. Participants having taken an investigational drug within 30 days prior to screening.
6. Previous exposure to centanafadine.
7. Any history of significant bleeding or hemorrhagic tendencies.
8. A history of difficulty in donating blood.
9. The donation of blood or plasma within 30 days prior to the first dose of investigational medical product (IMP).
10. Use of prescription, over-the-counter, herbal medication or vitamin supplements within 14 days prior to the first dose of IMP and antibiotics within 30 days prior to the first dose of IMP.
11. Any participant who, in the opinion of the investigator, should not participate in the trial. Note: Other protocol-specified inclusion/exclusion criteria may apply.

Anonymized individual participant data (IPD) that underlie the results of this study will be shared with researchers to achieve aims pre-specified in a methodologically sound research proposal. Small studies with less than 25 participants are excluded from data sharing.

Data will be available after marketing approval in global markets, or beginning 1-3 years following article publication. There is no end date to the availability of the data.

Otsuka will share data on the Vivli data sharing platform: https://vivli.org/ourmember/Otsuka/