There are three Seeds of Will that you can find in Kamoshida Palace in Persona 5: Royal. These locations are hidden and if you locate them all you receive a reward for your dedication, which is the Crystal of Lust. If one of your party members equips this item, they gain the Diarama spell, which grants them a medium healing spell. It can later become the Ring of Lust if you give it to Jose in Memories.
To get the Crystal of Lust, you need to find the Red, Blue, and Green Will Seeds.
Red Will Seed
Luckily, you can’t miss this Will Seed, as it’s part of the walkthrough tutorial on how they work. After battling the Heavenly Punisher for the first time in the Chapel, you will progress to where Morgana draws your attention to an ivy covered door. You have to use your grappling hook to cross it, but when you do, you locate the red one.
Green Will Seed
The next seed of will is after reaching the roof of the palace. Your group will notice how closer you are to the location of the treasure, and then three heavily guarded shadows block your way in the courtyard. To get past them you have to stick to the shadows and then use your grappling hook to propel yourself above them. When you are on the roof, jump on it to head towards the tower.
You want to go until you reach the window opening taking you to the next part of the area. However, instead of moving forward, to the right of the window, you should see a small opening as you walk through. Browse and you will be able to access multiple platforms. When you reach the one with a treasure chest, use your third eye to locate a grappling hook. Jump up there and go through the next window to find the green seed.
Blue Will Seed
The third and final seed of will is closer to the end of the palate. Morgana will draw your attention to an elevator that has scantily clad women as pillars on either side. Go down the elevator and enter a room blocked by a Kamoshida painting. Run towards the art and you will come back to the central part of the castle. On the left side is a small room that you can enter that activates the gears in the palace, allowing you to continue to the blue seed room. You might want to use the save room on that left before you come back.
Now, after you’ve activated those gears and saved up, go back to how you walked through the paint. Instead of going up the elevator, take the left path and go down. You now have a clear photo of the Blue Seed, but there is a fierce shadow in front of you that cannot ambush. You and your teammates will need to remove it. Hope you saved.
When you have all three Seeds of Willpower, you should then obtain the Crystal of Lust, which you can donate and equip to any member of your party.