Obtained: During the Chapter 2 Intermission, accept a Topic from Maiko Shimazaki then head to Fortuna Office to speak with her in person.
After accepting the side story, head to Tiki in Bloom Palace to ask her for a hangover remedy. Agree to go to the Idolasphere to collect some ingredients for Tiki to make the medicine with. Once you receive a Topic from Tiki, head to the Idolasphere in Daitama to collect Illusory Fungus, Illusory Clams and Illusory Dirt. After you enter the Idolasphere, keep following the path forward. You will head down the elevator and drop down a ledge. After you drop down, you can find the Illusory Fungus on the ground before entering the circular observatory chamber. To find the next item, pass through the chamber and take a right to follow the path forward. You will pass a short dead end on your right then come to another path leading right. Follow this path to the right to find the Illusory Clams. For the last item, turn around and take the next available right to find an elevator leading up. Jump on and head on up! Keep pressing forward until you reach the green healing pillar to the left of the brightly lit boss chamber. The Illusory Dirt will be on the ground in front of the green healing pillar. Once you have collected all of the items, head back to Bloom Palace and hand them over to Tiki to trigger a cutscene.