This is a slide for CloudNative Days Tokyo 2021 Keynote (https://event.cloudnativedays.jp/cndt2021/talks/1208). At Mercari, we've been building internal development platform top on Kubernetes and Cloud-native ecosystem for more than 3 years. The history of building the platform is the history of security hardening. In this session, I'm going to introduce what kind of security hardening we've imple