Similar to other families pools, this pool feature pictures of the family of Yui from Sword Art Online, (i.e.) Kirito, Asuna (sao) and Yui (sao) doing family-like activities.
Pictures with just some of the 3 characters present are not enough to be in this pool; the pictures need to have a family-like touch.
As long the family concept is present, the 3 characters don't need to be in the image, ie. Asuna behaving like a mom with Yui, without Kirito is valid.
(And other characters can be present as long they don't conflict with the family concept of those 3)
The pool is named after Yui, because if it were named after Kirito or Asuna, it could give the impression that is about Kirito's or Asuna's real life families.
