What is the Camellia Society in NTE? How to join?

The Camellia Society is a mysterious NPC organization in NTE that plays a significant role in the main story. It's a secret society of Espers in the city with a complex relationship with Eibon Antique Shop. Players encounter the Camellia Society storyline after reaching Main Story Chapter 4. Joining requires completing specific main and side quest chains, which unlocks exclusive quest lines and a limited shop.