On February 1st, the Original Soundtrack and Art Setting Collection were released.
The Soundtrack includes all the music from "Rainy Day."
https://store.steampowered.com/app/3486640/_/
The Art Setting Collection includes the design concepts and artistic settings.
(Currently, the Art Setting Collection is only available in Chinese, but the English version will be updated soon.)
https://store.steampowered.com/app/3486640/_/
If you want to support "Rainy Day," you can purchase the DLC.
Both DLCs will be discounted during sales, so you can buy them at a lower price during those periods.
Thank you, everyone!