JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://nelog.jp/wp-content/themes/simplicity-child-nelog/style.css">
<div id="the-content" class="entry-content">
    <div class="eye-catch">
        <img title="" src="http://nelog.jp/wp-content/uploads/2015/11/b150c72a-bebb-4804-a756-3892321cc976.png" alt="寝ログの画像をパクってます" height="313" width="680">
    </div>
</div>

CSS

.eye-catch {
    position: relative;
    padding: 0;
    margin: 0;
}
.eye-catch img {
    display: block;
}

.eye-catch .eye-caption {
    position: absolute;
    bottom: 0;
    right: 0;
    font-size: 12px;
    background-color: #000;
    padding: 0 5px;
    color: #fff;
    font-style: italic;
}

JavaScript

(function ($) {
    $(function () {
        var caption = $(".eye-catch img").attr("alt");
        $(".eye-catch").append("<div class='eye-caption'>" + caption + "</div>");
    });
})(jQuery);