Your code works for me here. I think you are missing the font you specified. This works, 2 labels shown, both Japanese, different fonts.

#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw=tkinit;

$mw->fontCreate('big',
     -family=>'arial',
     -weight=>'bold',
     -size=> 38
    );

my $string = "\x{65E5}\x{672C}\x{8A9E}\x{306E}\x{3072}\x{3089}\x{304C}
+\x{306A}\x{6F22 }\x{5B57}\x{3068}\x{30AB}\x{30BF}\x{30AB}\x{30CA}";

my $label = $mw->Label(-bg => 'white',
                       -text => $string, 
                       -font => 'big')->pack();


my $label1 = $mw->Label(-bg => 'white',
                       -text => $string, 
                       -font => "-adobe-helvetica-regular-r-normal-*-1
+2-*-*-*-*-*-*-*")->pack();

MainLoop;
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