This is for using every item on the item screen in your inventory atleast once. There are a total of 12 items to use. You should naturally pick all of the items up of enemies throughout your journey. I will list them then check out my video if you need more explanation.
1. Potion
2. Auto-Potion
3. Monster Milk
4. Super Monster Milk
5. Flesh Pop
6. Meat Chunklet
7. Bento Box
8. Lobster Tail
9. Pirate Flare
10. Bubble Shield
11. Pike Ball
12. Super Pike Ball