Solution : https://service.sap.com/sap/support/notes/821408 (SAP Service marketplace login required)
Key words : 
personnel management -> personnel administration        -> payroll data -> basic pay -> check pay scale area    pay scale area    pay sce area text    -----------------------------------    01                ’à‹à•\ƒgƒšƒa‚, personnel management -> personnel administration        -> payroll data -> basic pay -> check pay scale type, scale type  pay scale type text    ---------------------------------    01            ’à‹à•\ƒ^ƒcƒv‚, 02            ’à‹à•\ƒ^ƒcƒv‚q2, pay scale area, pay scale type, 02                ’à‹à•\ƒgƒšƒa‚, 03                ’à‹à•\ƒgƒšƒa‚, restore destroyed japanese texts manually, proper japanese texts manually
Related Notes : 
       
| 544623 | New Installation of Unicode SAP systems |