There should be a tab for "Favorite" Familiars that you can put whichever ones you want on there.
As of now, if you want to collect a lot of familiars, it makes it harder to find the ones you use most commonly, having to scroll through pages and etc.
Also another unrelated suggestion;
Have quest items/event items that fill up etc space, use space, etc, appear in the cash shop tab instead of the tabs they fill up. Even with max inventory, having a full Use or Set up tab can make some events very difficult, and it would make more sense for event specific items to just be in the cash shop inventory, instead of filling up your actual inventory.
