Really excited for this! Will the updates and routes be on Steam as well?
Viewing post in Release Date: Fashionista Route & Live2D Results comments
Yes!
The Steam DLC will be separated into 2 separate purchases 1-2 weeks prior to release. Individually, they will cost a bit more, but there'll be a DLC bundle that lets you purchase the remaining route for a discounted rate, so in the end, it'll be the same price as on itch.io. That was the best solution I could come up with, although it's a bit more convoluted than I'd like.