I found it entertaining.

But when I finished I didn't have a better understanding of Japan's people, culture, or cuisine. Only a p-hack explained by multi-national marketing.

I understood that very small $ of Japanese people are not Christians and do not celebrate Christmas before; fast food isn't considered cheap terrible food in Japan (at least American fast food chains) and that they value family time together and created/adhered to a tradition of getting families together on a day they normally wouldn't before since perfect excuse to be with family.

That's good enough piece