Have you Ever Faced the Japanese URL Hack?

Have you ever faced the malicious japanese url issue on your website? if yes, how did you get rid of it?

Please share your experience and the steps you took to fix it. Your insights could help others who are dealing with same problem and looking for a solution.

We've had many threads about this over the years, check these for some previous insights:
https://www.blackhatworld.com/seo/w...ibberish-hack-or-chinese-spammer-etc.1600988/
https://www.blackhatworld.com/seo/got-japanese-query-hack-for-my-site-what-can-i-do.1588362/
https://www.blackhatworld.com/seo/need-help-with-those-darn-chinese-spammers.1454578/

Also check the forum's search function: https://www.blackhatworld.com/search/

It is usually caused by hacked pages being generated and indexed but not a normal SEO problem.
The fix typically involves cleaning the site files, removing spam URL and then requesting removals in google search console. After that updating sitemap and re crawling helps google clear them out over time. Prevention usually comes down to stronger security and keeping CMS/plugins updated.