Defeat Darkrane Kynari Guards, Darkrane Kynari Searchers, and Darkrane Kynari Combat Guards at Castor's Copse. Then, talk to Spektor at Tapaeon. Use your quest tracker to see your progress.
Spektor: The number of Darkrane Kynari is increasing. Spektor: Darkrane must be planning on catching Sir Hakks. NakanoAzusa: That must be. I can tell their number is increasing. Spektor: Kynari follow the High Castor at all costs. Giregg and Spektor: I follow Sir Hakks because we still believe Sir Isaiah Spektor: is the true High Castor. NakanoAzusa: I just hope that this war ends soon. Spektor: We Kynari are not afraid to shed blood to correct Spektor: something wrong. Don't humans also fight against Spektor: each other? NakanoAzusa: Hmmm.... Spektor: There aren't that many Kynari that follow Sir Hakks, it's Spektor: only the Kynari who received help from Sir Isaiah. I'm Spektor: sorry, but you must step in to help us.