Lifetime employment in Japanese public sector

Hi. I am writing an SF novel, which requires a lot of knowledge in sociology of a different countries and cultures. And though I know a lot about it, I am still missing some information. One of those is connected to to the concept of lifetime employment in Japan. I know that it is usual in corporative sector, but I need an information about public sector. So... If someone works, for example, in Japanese ministry of defense, is it possible for that individual to move to, let's say, ministry of economics? Just theoretically speaking... Thanks in advance.

it is possible but it's the same as any other career change, the jobs are different. it would be a fairly major change in the person's life and job description.

No Japanese public workers don't transfer. They do loaning tho.