Obtained: After Eleonora reaches Stage Rank 3, you will receive a Topic to meet her at Shibuya Station. Eleonora is standing under a tree so go on over there and speak to her.
After you accept the side story, head on over to the newly unlocked Classroom Film Set and talk to Eleonora again. After a Topic interruption from Maiko, you’ll find out that you two will be going on a date. Eleonora weirdly enough wants to do a bit of research in some magazines and will leave you behind. You can find her in Hee Ho Mart standing by the magazine rack. Go and speak with her there. She will then say she is thirsty and storm out expecting you to follow her again. This time she is standing in front of Cafe Seiren. Talk to her again to trigger a cutscene. She’ll run off again…no surprise there! She mentioned she wanted to check out the jewelry place so head on over to Jewelry Carabia and speak with her in front of the store. After a brief cutscene Eleonora will be able to unlock her Radiant Skill “Door of Affection” at Bloom Palace, so head on over there.