This was a great start to a visual novel, I really like where this is going! The art style is super pleasant and very cozy--I like that everything is quite soft and painterly. The backgrounds are excellent as well--I'm impressed with how many there are! It really set the scene. The lighting in particular is very nice, it feels quite cozy and lived in. The music was really enjoyable as well, almost had a nostalgic fantasy RPG quality to it. There's a nice level of detail and care in everything here, from the different sound effects when each character speaks, to the animations for the character portraits--lot of really nice touches that help it feel pretty polished!
Just some minor tweaks here and there--I only caught a single typo. I'd love a volume slider for the music, since it was a tad loud. The characters also seem to flicker translucent for a brief second when changing expressions--it's not super noticeable, but just distracting enough to notice. Not totally sure how this is related to decay at this stage beyond the mold=creature, but wouldn't be surprised if more of that is planned further in the storyline.
Overall, great job! It's a short snippet, but I'm really curious to see where this goes. I love the idea of something this cozy turning into horror, and I'm a little remiss we didn't get more of that, but I like the eerie bits we do have. The scene with the alchemist in particular was left me uneasy, so great job there. Can't wait to see more! :)