Coba gunakan font yang ditentukan alih-alih default, coba ini
<?php
$html2pdf = new HTML2PDF('P', 'A4', 'en', true, 'UTF-8');
$html2pdf->setDefaultFont('arialunicid0'); //add this line
$html2pdf->pdf->SetDisplayMode('fullpage');
$html2pdf->writeHTML($content, false);
$html2pdf->Output('japan.pdf');
?>
Referensi:http://community.impresscms.org/modules /newbb/viewtopic.php?post_id=43474#forumpost43474
