Luka is poor and has decided to do this quest for Amira in exchange for the information needs. Alternatively, he paid for the information but he spoke to Amira in the Pocket Castle after recruiting her and now he is doing this quest as a favor. Either way, Luka has to stop the trafficking of Phoenix Tails coming out from the Nameless Slums.
1: Head to the Nameless Slums. It can be accessed through a tunnel, west of Iliasville, north of Enrika and south of the four bandit's cave.
2: After making it through the tunnel, head south to the Nameless Slums. Enter it and the group decides to search for information on Don Dahlia by talking to people or just looking for her.
3: North East part of town, there is a tent, a meter south of the Weapon and Item shop. Enter the tent and talk to the women but she refuses to give you any information.
4: Leave the tent and go the bar at the North East part of town. In the bar, at the farthest end is a hooded man. He'll sell you information on where you can buy Phoenix Tails. He'll tell you to go to the tent and talk to the woman and the code word used for sales.
5: Go back to the tent and say the code word and the woman will reveal herself to be Don Dahlia. Finish the conversation and leave the tent.
6: Head to the south east part of town and there is a locked building. Clicking on the building plays a short cutscene where Don Dahlia enters the building.
7: Head back to the bar and talk to the second last person on the end of the bar. He'll steal the key for you.
8: Return to the locked building and enter it. And boss fight occurs and once you're done the smuggling operation is over.
9: Return to Amira.