Please refer to the following.
◎Teachme Biz Security Checklist
https://file.biz.teachme.jp/doc/teachmebiz_cloudservicelevel_checklist.pdf
◎IPA (Information-technology Promotion Agency, Japan)'s "How to Build a Secure Website 7th Revised Edition"
https://file.biz.teachme.jp/doc/ipa_checklist_v7_studist.pdf
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Related: Please tell us about your security initiatives.
https://help.teachme.jp/hc/en-us/articles/900005510626