We had an overseas client who had a permanent resident visa and wanted to consult us on re-entering Japan. According to the client, he left Japan more than a year ago.
The important point here is that even if you have a permanent resident visa, you have to apply for a re-entry permit before you leave Japan if you will be away from Japan more than a year. (If you are to come back within a year, you don’t have to go through this procedure as a special re-entry permit system is applied.) If you are away from Japan more than a year without having a re-entry permit, your permanent resident visa will be expired and your status will be back to the start. Very strict indeed.
When you are planning to leave Japan for a while, please don’t forget to consider applying for a re-entry permit even if you are a permanent resident!