1) The character dynamics are very good, they sound very natural in conversation and are pleasant to follow (namely I picked all the nice choices, if I did the mean ones Id probably think Sykes is too mean, as I did feel that for the non-choice dialogues[I'd never tell Erika to stfu]).
2) Erika is cute, I need more doses of her looks pls post any doodles you have of her, the singular sprite left me hungry for more (nvm found the doogles on toyhouse reading before posting is good)
3) I AM SYKES THE IMMORTAL (this is a tip based on how I saw it on a VN i played, but I think you could do the battle scene with slash animation cut-ins; I had the impression youd make a cg for each scene, which is a bit of a big investment, so just a suggestion to save your time and deliver the experience the same way, FX animation, a hurt sprite and good sounds sell a scene better than cgs can sometimes)
4) I don't know where the store might go from here, but Erika's mystery is interesting enough to make me want to see more. Who knows if she's the key to everything or just Act 1, but she was the biggest hook of Chap 1 to me.
5) Just played one game, will see how other choices spin out later, but I do appreciate when bad choices can lead you to a bad end, instead of just a branch dialogue that then resolves into the same event again. I think all vn players save 5 times whenever a choice pops up anyway, so theres no need to fear killing the player for a choice (doesnt even need to game over and title screen most of the time, just jump back to the choice screen after the bad end rolls).
6) You're a good writer.