There are, at most, about 90,000 Japanese people living or working in China at any given time. Students, engineers, office staff, families. To reach “half a million spies,” you’d need to turn every single one of them into an intelligence officer, then invent another 410,000 people who don’t exist.
So what’s the point of saying this?
It’s not about accuracy. It’s about atmosphere. Inflate the number until suspicion feels normal, until ordinary foreigners feel dangerous, until “counter-espionage” sounds like self-defense instead of paranoia.
This is how propaganda works when facts get in the way:
you don’t argue reality, you drown it.
When numbers stop describing the world, they start shaping it.