Inclusion Criteria:  1. Participant must have:  Been previously enrolled in soticlestat clinical study TAK-935-3001 (NCT04940624) or TAK-935-3002 (NCT04938427).  Exclusion Criteria:  Unstable, clinically significant neurologic (other than the disease being studied), psychiatric, cardiovascular, ophthalmologic, pulmonary, hepatic, renal, metabolic, gastrointestinal, urologic, immunologic, hematopoietic, endocrine disease, malignancy including progressive tumors, or other abnormality that may impact the ability to participate in the study or that may potentially confound the study results. It is the responsibility of the investigator to assess the clinical significance; however, consultation with the medical monitor may be warranted. Abnormal and clinically significant ECG abnormality at Visit 1 including QT interval with Fridericia correction method (QTcF) >450 milliseconds (ms) confirmed with a repeat ECG using manual measurement of QTcF. Participant is considered by the investigator to be at imminent risk of suicide or injury to self, others, or property. Participants who have positive answers on item numbers 4 or 5 on the CSSRS before dosing are excluded. This scale will only be administered to participants aged ≥6 years.