A Research Study Investigating Safety and Concentration in the Blood After One Dose Tablet of the New Medicine Monlunabant in Healthy Weight Japanese and Caucasian Men

Inclusion Criteria: * Male. * Age 18-55 years (both inclusive) at the time of signing the informed consent. * Considered eligible based on the medical history, physical examination, and the results of vital signs, electrocardiogram and clinical laboratory tests performed during the screening visit, as judged by the investigator. * For Japanese participants, both parents of Japanese descent and both paternal and maternal grandparents of Japanese descent. * For Caucasian participants, self-reported European descent or white Latin-American descent. * BMI 18.5-24.9 kg/m\^2 (both inclusive) at screening. Exclusion Criteria: * Known or suspected hypersensitivity to study intervention(s) or related products. * Previous randomisation in this study. * Previous rescreening for this study. * History of Major Depressive Disorder within the last 2 years from screening. * Presence or history of any psychiatric disorders (e.g., schizophrenia, bipolar disorder, eating disorders, depression, and anxiety) as judged by the investigator. * Suicidal ideation corresponding to type 4 or 5 or suicidal behaviour on the Columbia-Suicide Severity Rating Scale (C-SSRS) as assessed at screening or any history of suicidal attempts. * A Patient Health Questionnaire 9 (PHQ-9) score greater than 9 as assessed at screening.