Well the gentleman in question still had kids having presumably Japanese nationality even before obtaining citizenship, so not sure that's related.

It genuinely depends. The author refers to zainichi koreans, i.e. a pretty large population of koreans that ended up in Japan just before and during WW2. Quite a few of them are still not Japanese citizens despite having lived in Japan for several generations.

"Hanako, my lovely wife, should we settle down and have kids?"

"I want nothing more than to raise a family, but alas I simply can't face brining a child into a world in which people applying for citizenship in this country have to present such a long list of documents."

"I feel the same way, honey."