From what I remember off of Google translate the developers planned to write story scenarios centered around the heroine taking requests from NPCs. Basically the heroine is someone the nearby villagers rely on for help from anything like finding a lost kid to subjugating monsters. Later events may involve capture, possession, and other dark themes. Just the other day the developers finished up an early design of what conversations will look like.
If you haven't seen her already, the girl on the right (Hana) is supposed to be a NPC who stays behind in the church to offer support outside of combat. There's already a "defeated portrait" of her drawn, however it seems that developers are still deciding whether she'll have any scenes in the first release. Like the main heroine (Lilia) there's plans for her to be voiced. I've no idea if the characters will have voiced dialogue or just voiced sound effects like in the last game.