FOUR SEA TREASURE
1. Pick up the shiny objects in Underwater Cave. They are indicated as yellow stars in the map.
2. Once you collected all four, place them in your Handbook.
3. You will also be getting an Ultimate Treasure's Air for every shiny object. You'll get a total of four of these. You can see it in your quest bag.
4. Head to this NPC and give all your Ultimate Treasure's Air.
5. The shell should open up like this.
6. It will give you the The Azure Heart. Place it in your Handbook.
7. Done!
