https://doujinblog.org/c68-%e5%90%8c%e4%ba%ba%e8%aa%8c-%e3%82%a2%e3%82%ab%e3%82%bf%e3%83%9e-%e3%83%8a%e3%83%9e%e3%82%a4%e3%82%ad%ef%bc%81critical-state/