Here you can assign character, weapon symbol, soul symbol, support party, and Idola. Idola setup is unlocked on player rank level 6.
You can rapidly increase the number of materials assigned by holding down on the material's icon.
With the exception of The Warrior, Destiny Bonus, a stat bonus can be activated by having two copies of a character, one sided with law and the other sided with chaos. It is thus recommended to keep two copies of a character.