You tell Soroban of your situation and he recommends that you to present your case to the village leader, Bunchin.

Requirements

This quest is available if you have completed the quest Under the Sea.

Starting the Quest

Talk to Soroban in Tamamizu in the Ruby Sea to begin the quest.

Speak with Bunchin

Go west and attune to the Tamamizu Aetheryte, then go to the quest icon on the map and talk to Bunchin. There will be a cutscene.

Speak with Soroban

Talk to Soroban to proceed.

Slay an Unkiu

Go east up the slope and up through the cavern. When you find a fountain of water, stand on it to be launched up to the exit of the cave. The locations of Unkiu will be marked on the minimap. Slay them until you get a carapace.

Deliver the Unkiu Carapace

Go northwest into the cave, go left down the slope, go into the tunnel at the end, and go to where the orange arrow is pointing in the minimap. Talk to Soroban to hand over the Unkiu Carapace and complete the quest. There will be a cutscene.

Aether Current Quest

With the completion of this quest, you can now start the blue quest "The Sword in the Stone" in the Ruby Sea. Completing that quest will attune you to an Aether Current in this area.

Next Main Scenario Quest

After you complete the quest, you will need to be at least level 63 to proceed to the next quest. After you reach level 63, talk to Soroban to accept the next quest: In Soroban We Trust.