A Study to Assess the Safety, Tolerability, Pharmacokinetics, Immunogenicity, and Pharmacodynamics of E2025 in Healthy Participants

Inclusion Criteria: * Non-smoking, male or female age greater than or equal to (\>=) 18 years and less than or equal to (\<=) 55 years old at the time of informed consent. Females must be of nonchildbearing potential * Body weight \>=50 kilogram (kg) and a Body Mass Index (BMI) \>=18 and less than (\<) 30 kilogram per square meter (kg/m\^2) at Screening Exclusion Criteria: * Females who are breastfeeding or pregnant at Screening or Baseline; Females of childbearing potential. * Males who have not had a successful vasectomy (confirmed azoospermia) if their female partners are of childbearing potential and are not willing to use a highly effective contraceptive method throughout the study period or for 203 days after their partner's study drug administration. * Clinically significant illness that requires medical treatment within 8 weeks or a clinically significant infection that requires medical treatment within 4 weeks of dosing * 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 * Any clinically abnormal symptom or organ impairment found by medical history at Screening, and physical examinations, vital signs, ECG finding, or laboratory test results that require medical treatment at Screening * A prolonged QT/QTc interval (QTcF \>450 millisecond \[ms\]). A history of risk factors for torsade de pointes or the use of concomitant medications that prolonged the QT/QTc interval * Persistent systolic blood pressure (BP) greater than 130 millimeter of mercury (mmHg) or diastolic BP greater than 85 mmHg at Screening or Baseline; Heart rate less than 50 or more than 100 beats per minute at Screening or Baseline * Any lifetime history of suicidal ideation or any lifetime history of suicidal behavior as indicated by the Columbia-suicide Severity Rating Scale (C-SSRS) or equivalent scale or via interview with a psychiatrist * Any lifetime history of psychiatric disease (including but not limited to depression or other mood disorders, bipolar disorder, psychotic disorders, including schizophrenia, panic attacks, anxiety disorders); any current psychiatric symptoms as indicated by a standard screening tool. * Known history of clinically significant drug allergy; known history of food allergies or presently experiencing significant seasonal or perennial allergy at Screening * Any history of hypersensitivity reaction to a foreign protein, with clinical features not limited to nasal or conjunctival symptoms such as in allergic rhinitis * Known to be human immunodeficiency virus positive and/or active viral hepatitis (hepatitis B core antibody \[HBcAb\], hepatitis B viral protein \[HBcAg\], hepatitis B surface antigen \[HBsAg\], hepatitis C virus antibody \[HCVAb\]) as demonstrated by positive serology at Screening * History of drug or alcohol dependency or abuse within the 2 years before Screening, or a positive urine drug test or breath alcohol test at Screening or Baseline * Currently enrolled in another clinical study or used any investigational drug or device within 28 days (or 5\*the half-life, whichever is longer) preceding informed consent * Receipt of blood products within 4 weeks, or donation of blood within 8 weeks, or donation of plasma within 1 week of dosing * Exposure to any biologic drug within 90 days or at least 5 half-lives (whichever is longer), or within 4 weeks for vaccines, before Screening, with the exception of flu (7 days before dosing) and COVID-19 vaccination (14 days before dosing until after the Follow-up visit). * Any contraindication to continuous CSF sampling via indwelling lumbar catheter or via lumbar puncture (LP) * Participants identified at risk for hemorrhage. * Inadequate venous access that would interfere with study drug administration or obtaining blood samples * Participants who contravene the restrictions on concomitant medications, food, beverages, physical activities, and others as defined in the protocol