Japanese work culture is brutal as hell. They have a word called karoshi which means death by over work.

Men are very overworked and Japanese women are said to be generally very cold and uncaring. They are said to display extreme levels of hypergamy.

Many Japanese women expect their husband to give absolute control of finances to them.

Some wives gives husbands a paltry allowance from his own fucking salary that he earned.

When all these factors come together, of course Japan would have many MGTOWs.

I have never been to Japan myself but I heard about this from Japanese MGTOWs.