• CSS

.vertical {
  -webkit-writing-mode: vertical-rl;
  -moz-writing-mode: vertical-rl;
  -ms-writing-mode: vertical-rl;
  writing-mode: vertical-rl;
}

• HTML

<p class="vertical">古池や蛙飛びこむ水の音<br />芭蕉</p>

古池や蛙飛びこむ水の音
芭蕉