The pathology is different in Japan. Japanese otaku incels are a very different breed to the angry ones on Reddit (they call it sekkusu shinai shokogun, celibacy syndrome, and it's societally endemic in the under 40s). You can see it happening in a lot of fiction that panders to them.
Ever notice how romantic and especially moe anime has leaned more and more heavily on imoutocon in recent years?
It's because there's a significant market of young Japanese men who are so bad at meeting and speaking to women that they literally cannot buy into a romantic scenario coming out of anything other than a pre-existing familial relationship, because those are the only women they ever get to know well enough.
Bear in mind we're talking about a nation where 61% of unmarried men 18-34 are not in a relationship (49% of unmarried women) and one third of under 30s have never dated at all.