A Phase III Trial of Z-338 in Paediatric Patients With Functional Dyspepsia

Main Inclusion Criteria: Part 1\& Part 2 * Subjects aged from nine to 17 years (from nine to 14 years in Part 1), on the day the informed consent is signed. * Subjects with a diagnosis of FD as defined by the Rome IV Criteria. * Subjects who have postprandial fullness, upper abdominal bloating or early satiation. Part 2 only * Subjects who have postprandial fullness, upper abdominal bloating or early satiation during with a certain severity during a week prior to the day of randomization. Main Exclusion Criteria: Part 1\&Part 2 * Subject who have organic diseases of the gastrointestinal tract or gastrointestinal bleeding within 24 weeks prior to informed consent. * Subject who have received Helicobacter pylori eradication therapy within 24 weeks prior to informed consent, or subjects who is defined as Helicobacter pylori-positive within 4 weeks prior to or on the day the informed consent is signed. * Subjects who have alarm symptom on the day the informed consent is signed. * Subjects who have food allergy of unknown origin or uncontrolled food allergy. Part 2 only * Subject taking drugs used for FD within 2 weeks prior to the day of randomization (excluding proton pump inhibitors) * Subject taking proton pump inhibitors within 4 weeks prior to the day of randomization.