gistfile1.pl

#!/usr/local/bin/perl
my $codec = [
    [ qw(あ い う え お) ],
    [ qw(か き く け こ) ],
    [ qw(さ し す せ そ) ],
    [ qw(た ち つ て と) ],
    [ qw(な に ぬ ね の) ],
    [ qw(は ひ ふ へ ほ) ],
    [ qw(ま み む め も) ],
    [ 'や', undef, 'ゆ', undef, 'よ' ],
    [ qw(ら り る れ ろ) ],
    [ 'わ', undef, 'を', undef, 'ん' ],
];

my $ret = '';
foreach my $point (split(/\//, $ARGV[0])) {
    if ($point =~ /(\d)(\d)(\d)(\d)/) {
        $ret .= $codec->[ $1 * $2 ]->[ $3 * $4 ];
    }
}
print $ret, "\n";