https://www.php.net/manual/ja/function.mb-ucfirst.php
PHP: mb_ucfirst - Manual
phpmbmanual
https://perldoc.perl.org/5.42.2/functions/ucfirst
ucfirst - Perldoc Browser
browser
https://wiki.php.net/rfc/mb_ucfirst
PHP: rfc:mb_ucfirst
phprfcmb
https://www.w3schools.com/php/func_string_ucfirst.asp
PHP ucfirst() Function
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