Phase 1 TAK-906 Single and Multiple Ascending Dose Study in Japanese Healthy Male Participants

Inclusion Criteria

• In the opinion of the investigator or sub-investigator, the participant is capable of understanding and complying with protocol requirements.
• The participant signs and dates a written, informed consent form prior to the initiation of any study procedures.
• The participant is a Japanese healthy adult male, aged 20 to 60 years, inclusive, at the time of informed consent.
• The participant weighs at least 50 kilogram (kg) and has a body mass index (BMI) from 18.5 to 25 kilogram per square meter (kg/m^2), inclusive at Screening.
• A male participant who is nonsterilized and sexually active with a female partner of childbearing potential agrees to use adequate contraception from the signing of informed consent to 12 weeks (84 days) after the last dose of study drug. The female partner of a male participant should also be advised to use adequate contraception.

Exclusion Criteria

• The participant has received any investigational compound within 16 weeks (112 days) prior to the first dose of study drug.
• The participant has received TAK-906 in a previous clinical study or as a therapeutic agent.
• The participant is an immediate family member of or an investigational site employee, or is in a dependent relationship with an investigational site employee who is involved in the conduct of this study (example, spouse, parent, child, sibling) or may consent under duress.
• The participant has uncontrolled, clinically significant neurologic, cardiovascular, pulmonary, hepatic, renal, metabolic, gastrointestinal, or endocrine disease or other abnormality, which may impact the ability of the participant to participate in the study or potentially confound its results.
• The participant has a history of any psychiatric disease that would interfere with the evaluation of study drug activity (prolactin concentration) or safety.
• The participant has a history of seizure or tardive dyskinesia.
• The participant has a history of hyperprolactinemia, pituitary adenoma, and/or hypothyroidism.
• The participant has a family history of prolonged QT.
• The participant has undergone previous gastric bypass surgery or currently had a gastric band fitted.
• The participant has dysphagia and/or inability to swallow study medication whole.
• The participant has a known hypersensitivity to any component of the TAK-906 formulation or related compounds.
• The participant has a history of drug abuse (defined as any illicit drug use) or a history of alcohol abuse within 2 years prior to the Screening visit, or is unwilling to agree to abstain from alcohol and drugs throughout the study, or has a positive urine test result for drugs of abuse or a positive alcohol screen (urine alcohol test/breath test) result for alcohol at Screening.
• The participant has taken any excluded medication, supplements, or dietary products during the time periods listed in the Excluded Medications, Supplements, and Dietary Products table.
• If male, the participant intends to donate sperm during the course of this study or for at least 12 weeks (84 days) after the last dose of study drug.
• The participant has current or recent (within 24 weeks [168 days]) gastrointestinal disease that would be expected to influence the absorption of drugs (that is, a history of malabsorption, esophageal reflux, peptic ulcer disease, erosive esophagitis, frequent [more than once per week] occurrence of heartburn, or any surgical intervention).
• The participant has a history of cancer, except basal cell carcinoma which has been in remission for at least 5 years prior to Day 1.
• The participant has a positive test result for hepatitis B virus surface antigen (HBsAg), hepatitis C virus (HCV) antibody, human immunodeficiency virus (HIV) antibody/antigen, or serological reactions for syphilis at Screening.
• The participant has used nicotine-containing products (including but not limited to cigarettes, pipes, cigars, chewing tobacco, nicotine