In order to create the Nebula Core, you must first obtain two key items in the main story.

Here are the requirements you must clear in order to synthesize the Nebula Core:

1. Clear the “Searching for Memories 1” quest: You will need to obtain the Old Accessory in order to clear this quest.
2. Clear the “Searching for Memories 2” quest: In order to clear this quest, you will need the Old Scroll.
3. Complete the “Star Bud” entry in the Sunken City of Stars’ exploration diary: You will obtain the Nebula Core recipe as a reward.
4. Collect the ingredients: Aside from the Old Scroll and the Old Accessory, you will also need a Magical-type ingredient and a Star Fragment.

Obtaining the Nebula Core Recipe

The Nebula Core recipe is a reward for completing the Star Bud’s Ruin Crystal. You will have to complete two entries.

For the first entry, “The Teacher and the Student”, you will need the following memory fragments:

• The “Guiding Star Pendant” fragment, with the keywords “pendant” and “Guiding Star”.
• The “Disciple’s Memory 1” fragment. It contains the keywords “girl who lost her home” and “follow the Starchild”.
• The Disciple’s Memory 13” fragment. Its keywords are “Starchild’s disciple”, “farewell” and “master”.

For the “End of the City of Stars” Ruin Crystal, you will need these memory fragments:

• The “Starchild’s Memory 7” fragment. It contains the keywords “flood came down upon the City of Stars” and “Stachild chose to stay behind”.
• The “Starchild’s Memory 1” fragment. Its keywords are “floating island fell from the sky”, “mysterious being” and “neither human nor monster”.

Once you complete these two Ruin Crystals, return to the Atelier. You will automatically obtain the Nebula Core recipe.

Gathering the Ingredients

You will need to obtain two key items, the Old Accessory and the Old Scroll. The recipe also requires a Star Fragment and a Magical-type ingredient.

Obtaining the Old Accessory

You will obtain the Old Accessory by clearing the quest “Searching for Memories 1”.

Fast travel to Sunken City of Stars – Stargazing Upper Town. Take the door to the west.

On the next floor, walk north from the entrance and head up the set of stairs. Continue up the spiral stairway.

After going up the stairway, continue to the south. Walk to the end of the floor.

Once you reach the end of the floor, walk east and up the next staircase.

At the top of the staircase, a cutscene will play. You will then automatically obtain the Old Accessory.

Obtaining the Old Scroll

In order to obtain the Old Scroll, you must clear the “Searching for Memories 2” quest.

Head to the Sunken City of Stars – Stargazing Upper Town and take the door to the east.

On the next floor, head south and up the staircase.

Keep heading south, then continue up the next staircase.

After climbing up the stairs, head east.

Continue to the end of the floor. Walk up the staircase to the north.

You will reach a garden at the top of the staircase. Walk to the west.

Next, head north until you reach the end of the garden. You will find three empty bookshelves to your right.

Walk towards the bookshelves in order to trigger a cutscene. You will then automatically obtain the Ancient Scroll.

Gathering the Star Fragment

Fast travel to the Sunken City of Stars – Stargazing Lower Town. Use the Woodcutter’s Axe on the yellow crystals to obtain the Star Fragment.

For the Magical-type ingredient, you can collect Ether Aqua. You will obtain it by using the staff on the pots scattered around the Lower Town.

Synthesizing the Nebula Core

After collecting all ingredients, return to the Atelier. Use the cauldron and select the Nebula Core recipe.

Start by inserting the Old Scroll in the Quality loop to the bottom.

Insert the Star Fragment in the Quality loop to the left.

Add the Old Accessory to the Quality loop on the right side of the recipe.

Finish off the recipe by inserting an Ether Aqua in the top Quality loop.

After that, press the “Synthesize” button to complete the recipe.

Once you obtain the Nebula Core, you will be able to advance the main story. Head back to the Sunken City of Stars – Stargazing Upper Town and deliver the item to the Starchild.