1. The baseline tests (sleeping tendency assessment, clinical symptom and cognitive assessments, clinical laboratory tests, genotyping, exploratory biomarker tests, etc.) are conducted to the schizophrenia patients before initiation of the clozapine dosing.
2. On day 15 and 57, the changes from baseline clinical symptom and cognitive function are assessed after clozapine treatment. Also, the occurrence of adverse drug reactions are evaluated. In addition, blood sample collections are performed for the assessment of clozapine and its metabolite levels.