https://doujinblog.org/%e5%90%8c%e4%ba%ba%e3%82%bd%e3%83%95%e3%83%88-100116-constructor-%e3%83%aa%e3%83%bc%e3%83%b4%e3%82%a7%e3%83%ab%e3%82%a8%e3%82%b9%e3%83%86%e3%83%bc%e3%83%88-the-2nd-engagement/