Once you have confirmed that your website has been hacked, take action to fix it. The following steps you need to follow to remove the Japanese keyword hack and fixing your hacked website:
1. Manual audit
2. Remove newly created accounts on the Google search console.
3. Run a scan
4. Check and fix the .htaccess file.
5. Check and fix the WordPress configuration database connection strings.
6. Check and fix recently modified files.
7. Replace core files, plugin files, and theme files
8. Check upload directory
9. Check Sitemap
10. IP blockage
11. Remove URLs from Search Console
12. Configure robot text
13. Add Security plugins
14. Configure SSL certificate