Okamoto Hidetaka

This plugin gives you Related Item Widget and function.
If you want to show Related Item List, you can do following actions:
<ul>
<li>Add <code>Elasticommerce Related Widgets</code> in your widgets area.</li>
<li>Add <code>escr_related_item();</code> function in your theme or plugins.</li>
<li>If you only want to get the data, you can use <code>escr_get_related_item();</code> function.</li>
</ul>
Notice 
This plugin requires WooCommerce Plugin , so please install it. If WooCommerce Plugin is not installed or activated, this plugin will not work.
Required 
This Plugin cannot use Elasticsearch version 2.x. Please use Elasticsearch version 1.5 instead.

Elasticommerce Related Items

You can get good Related Item List powered by Elasticsearch.

Elasticommerce Related Items vs ElasticPress