$ perl -wE'use Devel::Peek;
use utf8;
use Encode;
my $str = "\303\244";
my $substr = substr($str, 0, 1);
Dump $substr;'
SV = PV(0x9b9f6c8) at 0x9bbca70
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  PV = 0x9bc0978 "\303"\0
  CUR = 1
  LEN = 4