In Jangan, go to the fountain in the town square. She's standing right by it, on the Western most side of it, facing the West gate.
Incidentally there is ANOTHER So-Ok NPC in the town, in the Barrom street area, who has nothing to do with the event, and doesn't even mention it. I guess the developers meant to move that NPC to the fountain for the event, but they forgot to remove the old version