Looking good, really promising start! Looking forward to future updates.
As for suggestions, I can think of a couple:
1. More sound effects is a must, I think they'd add a lot.
When the log says 'Aster follows closely' (or whatever it says), that implies there's a chance for her and Mentor to lag behind a room. So maybe have a chance for the two to disappear from the animations and just have the player hear them while the hero fights by himself? And then you can either go looking for them or wait for them to catch up?
2. The selling point of the game is the interactions with the light levels so I think you should lean into that as much as possible (e.g. random events that affect the light level, or that only occur at certain light levels (beyond just different animations, although that's a part of it).
Maybe try and implement an in-game reason to have lower light levels rather than just that you can't afford torches. Something like you can find more loot if it's darker? Then you can have Aster and the Hero discuss this with the Mentor, who encourages them to explore in the dark (for his own reasons too of course).
I'm thinking Darkest Dungeon kind of things, if you've played that. You could also maybe have some kind of stress meter or hallucination effects for the hero (some of which might not be hallucinations), but that might be a bit much.
I'm not sure how technically feasible it is, but I'd love to have unique animations for when the light level is increased during a scene. e.g. Aster suddenly realising you can see her and quickly adjusting her clothes while blushing.
Anyway, those might be ideas for the far future. I'd focus on just getting the main mechanics streamlined and some more content in for now, but it's looking good so far!