A Study of Intravenous Perampanel in Japanese Participants With Epilepsy

Inclusion Criteria: 1. A diagnosis of epilepsy with POS (including secondarily generalized seizures) or PGTC seizures according to the International League Against Epilepsy (ILAE) Classification of Epileptic Seizures (1981). 2. Receiving a stable dose regimen of oral perampanel. 3. Receiving a concomitant stable dose regimen of marketed AEDs. No change of dosing regimen for concomitant AEDs is planned during the intravenous Treatment and Follow-up Phases. 4. Considered reliable and willing to be available for the study period by the investigator, and are able to record seizures and report AEs by themselves or have a caregiver who can record seizures and report AEs for them. Exclusion Criteria: 1. A history of drug or alcohol dependency or abuse. 2. A history of status epilepticus. 3. Unsuitable for venipuncture and intravenous administration. 4. Requires medical intervention due to safety issues related to concomitant administration of AEDs. 5. A history of suicidal ideation/attempt. 6. Clinical symptoms or imaging suggest progressive central nervous system (CNS) abnormality, disorder, or brain tumor. 7. Current evidence of clinically significant disease (example, cardiac, respiratory, gastrointestinal, renal disease) that in the opinion of the investigators could affect the participant's safety, interfere with the study assessments or need prohibited medications as specified in the study protocol. 8. Clinically significant abnormal laboratory values. 9. Females of childbearing potential who: * In the Pretreatment Phase, are breastfeeding or pregnant (as documented by a positive beta-human chorionic gonadotropin \[β-hCG\] test). * Within 28 days before Visit 1, did not use a highly effective method of contraception, which includes any of the following: * total abstinence (if it is their preferred and usual lifestyle). * an intrauterine device (IUD) or intrauterine hormone-releasing system (IUS). * a contraceptive implant. * an oral contraceptive (with additional barrier method). (Participant must be on a stable dose of the same oral contraceptive product for at least 28 days before Day 1 of the Treatment Phase and throughout the entire study period, and for 28 days after the last dose of study drug). * have a vasectomized partner with confirmed azoospermia. * Do not agree to use a highly effective method of contraception (as described above) throughout the entire study period and for 28 days after the last dose of study drug. 10. Participation in a study involving administration of an investigational drug or device within 28 days before Visit 1, or within approximately 5 half-lives of the previous investigational compound, whichever is longer. 11. A prolonged QT interval corrected using Fridericia's formula (QTcF) interval (greater than \[\>\] 450 millisecond \[ms\]) as demonstrated by a repeated ECG. 12. A vagus nerve stimulation (VNS) implanted.