First complete the Finale: Ephemera mission, then display the following alternate inventories by pressing the D-pad in the corresponding direction five times at the inventory screen before starting a mission:

INVENTORY - DIRECTION
Black Ninja Flame , Explosive Sushi +300 (5), Powerful Land Mine (5), Cicada Shell - Press DOWN(5).
Short Grapple Hook, Strength Potion +90 (10), Knockout Sushi +90 (10), Speed Potion +90 (10) - Press LEFT(5).
Grapple Hook, Asuka Shuriken (30), Weak Land Mine (10), Health Potion +60 (20) - Press RIGHT(5).
Default mission inventory - Press UP(5).