The screen after choosing the creature cage.

The Creature Cage is a part of of the Main Menu interface. You gain access to it when you get your first Familiar. You get your first familiar after usng the Form Familiar spell the Old Father Oak gives you.

What to Do Here

You may feed your familiar treats. Each treat has a number of squares that determine how much of the stat meter will fill up and a fullness. At the same time, the familiarity level will rise up, providing bonuses as each heart becomes full.

Chocolate affects attack.

Flan affects defense.

Cake  affects magical attack.

Sundae affects magical defense.

Pie affects accuracy.

Ice cream affects evasion.

You may also feed your familiar a gem (provided that it is compatible). Gems provide new moves to familiars.