Flen in Black

Chika grows medicinal herbs and sometimes helps treat her fellow villagers. One day, she notices someone dressed from head to toe in black standing in her herb garden. It turns out that person’s name is Flen, and she also seems to be extremely knowledgeable about medicines and herbs. Chika invites her in for a drink and asks her where she’s from. Flen replies with the mysterious answer “over the eastern mountain, and then as far as east goes.” However, it seems there is a secret behind Flen’s amazing medicinal knowledge. What could it be?