<!DOCTYPE html>
<html lang="ja">
<head>
  <meta charset="UTF-8">
  <style>
  html {
    -webkit-writing-mode: vertical-lr;
  }
  div {
    font-size: 40px;
    font-style: italic;
  }
  </style>
</head>
<body>
  <div style="position:absolute;color:red; top:0; left:0; clip:rect(32px, auto, auto, 32px)">丹</div>
</body>
</html>