A Comparative Study of KHK6188

Inclusion Criteria: * Patients with pain for ≥ 3 months and ≤ 1 year following onset of a herpes zoster rash * Patients with a mean pain intensity score (11-point numerical rating scale) of ≥ 4 * Patients whose rash has been healed * Patients who are able to fill their patient diary * Patients who provided written voluntary informed consent to participate in the study Exclusion Criteria: * Patients who have other pain or disease which may impair the self assessment of pain * Patients who have dementia, depression or schizophrenia which may affect the self assessment of pain * History or presence of severe cardiovascular disease, hepatic dysfunction, renal failure, respiratory disease, blood disease or CNS disorder * History or presence of a drug allergy * Patients who have a history of a diagnosis of cancer or a treatment of cancer within 5 years prior to the study entry * Patients received an investigational medication within 4 months (6 months for biologic medication such as antibody) prior to the informed consent * Women of child bearing potential who do not agree to avoid pregnancy from the time of providing the consent until 3 months after the end of dosing, or men of reproductive potential who do not agree to avoid pregnancy from the time of the first dose until 3 months after the end of dosing * Patients who are pregnant, lactating, or possibly pregnant * Patients judged to be inappropriate to enter the study by a investigator or a subinvestigator