What are all the extra inventory squares for?

[triphorce]

I see a full circle around my character's inventory--I asked and someone told me they are for pets. Can you hold a pet in every square? Or just 1 pet? Thanks!

[Asmodejjj]

You can only have 1 pet. The other spaces are for event items and such.

[Toonruler10]

1 for pets the others are usually used for events

[Marine-RX179]

They are for Costumes etc.