use HTML::Entities;
use Devel::Peek;
$c = decode_entities("&#12398");
Dump $c
__END__
SV = PV(0x91ecb00) at 0x91ebcdc
  REFCNT = 1
  FLAGS = (POK,pPOK,UTF8)
  PV = 0x91ff608 "\343\201\256"\0 [UTF8 "\x{306e}"]
  CUR = 3
  LEN = 8