I also looked into this a little more, and I believe these are out of date. It looks like it's much closer to evenly split than previously believed.

"A government survey has revealed that women make up almost half of the estimated 1.46 million people aged 15 to 64 who have withdrawn from Japanese society. It was previously believed that most of the recluses, known as hikikomori, were men." https://www3.nhk.or.jp/nhkworld/en/news/backstories/2391/ [April 2023]