Jiraiya,
You do 2 sim checks in your training here. The first one is the Type Rating Check. The second one is called your ATPL Check. You then get issued your Japanese ATPL.
You DO NOT have to do ATPL theory (assuming you already have an ATPL issued by another country that they accept). The only written exams you do are Japanese Air Law, 767 Systems and a radio exam. The radio exam was written back in the 50's by the look of it and it's a complete waste of time but it is a requirement!