Patient description: A 57-year-old man was admitted to the clinic because of weight loss and persistent dry cough 4 months ago. Chest computed topography showed bilateral multiple infiltrates in the upper lobes and thickened bronchial walls. There is a documented positive serum MPO-ANCA in his medical record. Transbronchial biopsy revealed necrotic granulomas with multinucleated giant cells and the Wegener's granulomatosis was diagnosed for him. He is treating with corticosteroid and cyclophosphamides since 4 months ago. His Birmingham Vasculitis Activity Score (BVAS) is above 4 since the beginning of his disease. His last physical exam and lab study was performed yesterday and showed the results bellow: A wellbeing, well-nourished man, non-icteric, cooperative and alert Weight: 73 kg Height: 177 BP: 120/80 HR: 90/min RR: 22/min Hgb: 13 g/dl WBC: 8000 /mm3 (Neutrophil: 2700/mm3) Plt: 300000 /ml AST: 40 U/L ALT: 56 U/L Alk P: 147 U/L Bill total: 1.2 mg/dl ESR: 120 mm/hr MPO-ANCA: 153 EU

Clinical trial eligibility criteria: eligible ages (years): 20.0-45.0,  Dose Finding Study Healthy adult Japanese male volunteer. 2. Is 20-45 years old inclusive, at time of giving consent. 3. Is capable of understanding and complying with protocol requirements. 4. Signs a written, informed consent form prior to the initiation of any study procedure. 5. Weighs at least 50 kg and has a body mass index (BMI) of 18.5 to 25.0 kg/m^2 inclusive at screening. 6. Tests negative for hepatitis B surface antigen (HBs), hepatitis C virus (HCV) antibody, human immunodeficiency virus (HIV) antigen-antibody and syphilis serum reaction test. 7. The participant who the investigator or subinvestigator confirmed to be eligible to participate in this study based on results of the screening tests, and physical examination, physical findings, vital signs, electrocardiogram (ECG), clinical laboratory tests etc. from 3 days before dosing to before the start of dosing on Day 1 with the study drug  Has undergone upper gastrointestinal resectioning or vagetomy. 2. Is judged to have hypoacidity or anacidity. 3. Presently has or a history of acid-related diseases (e.g., erosive esophagitis, duodenal ulcer, gastric ulcer, non-erosive esophagitis, Barrett's esophagitis or Zollinger-Ellison syndrome). 4. Received H. pylori eradication treatment within 6 months prior to the start of treatment with the study drug. 5. Presently has or has a history of hepatic disorder, renal disorder, cardiovascular system disease, blood disease, endocrine disease, metabolic disease, lung disease, gastrointestinal disease, nervous system disease, urological disease, immunological disease or mental illness that makes him not eligible to participate in this study. 6. Presently has or has a history of hypersensitivity or allergy towards drugs or food. 7. Has a history of drug abuse (defined as any illicit drug use) or a history of alcohol abuse within 5 years prior to the start of treatment with the study drug. 8. Participant for whom it is difficult to collect blood from the peripheral veins. 9. Has donated more than 200 mL of whole blood within 4 weeks (28 days) or more than 400 mL of whole blood within 12 weeks (84 days) prior to the start of treatment with the study drug. 10. Has donated a total volume of more than 800 mL of whole blood within 52 weeks (364 days) prior to the start of treatment with the study drug. 11. Has given plasma component and plaque component within 2 weeks (14 days) prior to the start of treatment with the study drug. 12. Has used a prescription drug (including over-the counter drugs) within 4 weeks (28 days) prior to the start of treatment with the study drug. 13. Has used vitamins, Chinese herbal remedies, or supplement (including St John's Wort, ginseng, kava kava, ginkgo biloba, melatonin) within 4 weeks (28 days) prior to the start of treatment with the study drug. 14. Has ingested any foods or beverages containing grapefruit (juice or pulp), caffeine, alcohol within 72 hours prior to the start of treatment with the study drug. 15. Administered another study drug within 16 weeks (112 days) prior to the start of treatment with this study drug. 16. Administered TAK-438 in the past. 17. Is considered by the investigator or subinvestigator, for any reason, to be an unsuitable candidate for participating in this study