A Study to Evaluate ASP0367 in Participants With Mild/Moderate Hepatic Impairment Compared to Participants With Normal Hepatic Function

Inclusion Criteria:

* Participant has a BMI range of 18.5 to 36.0 kg/m\^2, inclusive and weighs at least 50 kg at screening.
* Female participant is not pregnant and at least 1 of the following conditions apply:

  * Not a woman of childbearing potential (WOCBP)
  * WOCBP who agrees to follow the contraceptive guidance from the time of informed consent through at least 28 days after IP administration.
* Female participant must agree not to breastfeed starting at screening and throughout the study period and for 28 days after IP administration.
* Female participant must not donate ova starting at dose of IP and throughout the study period and for 28 days after IP administration.
* Male participant with female partner(s) of childbearing potential (including breastfeeding partner\[s\]) must agree to use contraception throughout the study period and for 28 days after IP administration.
* Male participant must not donate sperm during the study period and for 28 days after IP administration.
* Male participant with pregnant partner(s) must agree to remain abstinent or use a condom for the duration of the pregnancy throughout the study period and for 28 days after IP administration.
* Participant agrees not to participate in another interventional study while participating in the present study.

Additional Criteria for Participants with Hepatic Impairment:

* Participant has mild (Child-Pugh classification Class A, score 5 or 6) or moderate (Child-Pugh classification Class B, score 7 to 9) hepatic impairment at screening

Exclusion Criteria:

* Participant has received any investigational therapy within 28 days or 5 half-lives, whichever is longer, prior to day -1.
* Participant has had a partial hepatectomy within 1 year prior to screening.
* Participant has any condition which makes the participant unsuitable for study participation.
* Participant has a known or suspected hypersensitivity to ASP0367 or any components of the formulation used.
* Participant has received a COVID-19 vaccine within the 2 weeks prior to IP administration or will have a COVID-19 vaccine dose before the ESV.
* Female participant who has been pregnant within 6 months prior to screening or breastfeeding within 3 months prior to screening.
* Participant has had previous exposure with ASP0367.
* Participant has used moderate or strong inducers of CYP3A within the 3 months prior to day -1.
* Participant has used proton-pump inhibitors within the 2 weeks prior to IP administration.
* Participant has used Histamine-2 blockers within 24 hours prior to IP administration.
* Participant has any clinically significant history of allergic conditions (including drug allergies, asthma, eczema or anaphylactic reactions, but excluding untreated, asymptomatic, seasonal allergies) prior to IP administration.
* Participant has/had febrile illness or symptomatic, viral (excluding chronic hepatitis B virus and hepatitis C virus), bacterial (including upper respiratory infection) or fungal (noncutaneous) infection within 1 week prior to day -1.
* Participant has had significant blood loss, donated ≥ 1 unit (450 mL) of whole blood or donated plasma within 7 days prior to day -1 and/or received a transfusion of any blood or blood products within 60 days.
* Participant is an employee of Astellas, the study-related CROs or the clinical unit.
* Participant has a positive result for SARS-CoV-2 test at screening.
* Participant has creatinine level outside normal limits on day -1. In such a case, the assessment may be repeated once.

Additional Criteria for Participants with Hepatic Impairment:

* Participant has any history or evidence of any clinically significant cardiovascular, gastrointestinal, endocrinologic, hematologic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, renal and/or other major disease or malignancy not related to current disease state.
* Participant has cardiac troponin I (cTnI) \> upper limit of normal (ULN) (or cardiac troponin T \[cTnT\]) \> ULN if cTnI is not available). In such a case, the assessment may be repeated once.
* Participant has a mean pulse \< 45 or \> 100 bpm; mean systolic blood pressure \> 160 mmHg; mean diastolic blood pressure \> 100 mmHg (measurements taken in triplicate after participant has been resting in the supine position for at least 5 minutes; pulse will be measured automatically) on day -1. If the mean blood pressure exceeds the limits above, 1 additional triplicate may be taken.
* Participant has a mean QT interval using Fridericia's correction (QTcF) of \> 460 msec for male participants and \> 480 msec for female participants on day -1. If the mean QTcF exceeds the limits above, 1 additional triplicate ECG may be taken.
* Participant who has had a change in dose regimen of medically required medication(s) in the 2 weeks prior to screening (permitted concomitant medications) and/or participant for whom dose changes are likely to occur during the study (minor dose changes are allowed in agreement with the sponsor) and/or participant has used nonpermitted concomitant medication(s) in the 3 weeks prior to admission to the clinical unit (nonpermitted concomitant medications include any known hepatic enzyme-altering agents, compounds, vitamins or natural herbal remedies, e.g., St. John's Wort known to restrict metabolism).
* Participant has a history of consuming \> 14 units for male participants and \> 7 units for female participants of alcoholic beverages per week within 3 months prior to screening or has a history of alcoholism or drug/chemical/substance abuse within 1 year prior to screening (note: 1 unit = 12 ounces of beer, 4 ounces of wine, 1 ounce of spirits/hard liquor) or the participant tests positive for alcohol at screening or on day -1.
* Participant has used any drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and/or opiates) within 3 months prior to day -1 or the participant tests positive for drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and opiates) at screening or on day -1, unless the positive test is due to prescription drug use that is approved by the principal investigator and sponsor.
* Participant has a positive serology test for hepatitis A virus antibodies (IgM), hepatitis B surface antigen (HBsAg) or antibodies to human immunodeficiency virus type 1 and/or type 2 at screening.
* Participant has fluctuating or rapidly deteriorating hepatic function, as indicated by strongly varying or worsening of clinical and/or laboratory signs of hepatic impairment within the screening period (e.g., advanced ascites, infection of ascites, fever, active gastrointestinal bleeding).
* Participant has a presence of a hepatocellular carcinoma, or an acute liver disease caused by an infection or drug toxicity.
* Participant has severe portal hypertension or surgical portosystemic shunts, including transjugular intrahepatic portosystemic shunt.
* Participant has biliary liver cirrhosis, biliary obstruction or other cause of hepatic impairment not related to parenchymal disorder and/or disease of the liver.
* Participant has signs of significant hepatic encephalopathy (hepatic encephalopathy grade ≥ 2).
* Participant has severe ascites and/or pleural effusion.
* Participant has esophageal or gastric varices which have a high risk of clinically significant hemorrhage.
* Participant has thrombocyte level below 40 × 10\^9/L and/or hemoglobin \< 90 g/L.
* Participant has had previous liver transplantation.

Additional Criteria for Healthy Participants with Normal Hepatic Function:

* Participant has any of the liver function tests (alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase and total bilirubin) ≥ 1 × ULN or international normalized ratio \> 1.1 on day -1. In such a case, the assessment may be repeated once.
* Participant has cTnI \> ULN (or cTnT \> ULN if cTnI is not available) at screening.
* Participant has any history or evidence of any clinically significant cardiovascular, gastrointestinal, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, renal and/or other major disease or malignancy.
* Participant has any clinically significant abnormality following the physical examination, ECG and protocol-defined clinical laboratory tests at screening or on day -1.
* Participant has a mean pulse \< 45 or \> 90 bpm; mean SBP \> 150 mmHg; mean DBP \> 90 mmHg (measurements taken in triplicate after participant has been resting in the supine position for at least 5 minutes; pulse will be measured automatically) on day -1. If the mean blood pressure exceeds the limits above, 1 additional triplicate may be taken.
* Participant has a mean QTcF of \> 430 msec for male participants \> 450 msec for female participants on day -1. If the mean QTcF exceeds the limits above, 1 additional triplicate ECG may be taken.
* Participant has used any prescribed or nonprescribed drugs (including vitamins and natural and herbal remedies, e.g., St. John's Wort) in the 2 weeks prior to IP administration, except for occasional use of acetaminophen (up to 2 g/day), topical dermatological products (including corticosteroid products), hormonal contraceptives and hormone replacement therapy.
* Participant has a history of consuming \> 14 units for male participants and \> 7 units for female participants of alcoholic beverages per week within 6 months prior to screening or has a history of alcoholism or drug/chemical/substance abuse within 2 years prior to screening (note: 1 unit = 12 ounces of beer, 4 ounces of wine, 1 ounce of spirits/hard liquor) or the participant tests positive for alcohol at screening or on day -1.
* Participant has used any drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and/or opiates) within 3 months prior to day -1 or the participant tests positive for drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine and opiates) at screening or on day -1.
* Participant has a positive serology test for HAV antibodies (IgM), hepatitis B surface antigen, HCV antibodies or antibodies to HIV type 1 and/or type 2 at screening.