Related productsを移動したい

Hi,

You should not add your related products module in the "Modules to display under the main area" option of the configuration, but in the "Modules under the product page" option of the configuration as explained in the documentation:
www.hikashop.com/en/support/documentatio...ct-form.html#related

Inserting a module in descriptions can be done in several ways but it can pose some problems based on how you configure everything. So it's not possible to give a one size fit all solution.
For example, if you want to display add to cart buttons in your related products listing module, you will have to move the description display out of the form of the product page or the HTML elements will conflict and the add to cart buttons won't work properly.

The simplest solution though will be to use the joomla extension modules anywhere to insert a display tag for your related products module where you want in the description of each one your products.