All items are collected, the gallery is fully open. Steam version 1.3.1 was played.

Installation:

Download the archive with your save.
Disable cloud sync (if licensed, in Steam or another launcher).
Go to the following path: "AppData\LocalLow\Uu\SiNiSistar2\SaveData_S"
Unzip the archive contents to this folder (replace if necessary).
Launch the game.
Check your save.
Exit the game.
Enable cloud sync (if licensed, do the same as you disabled it).
If there is a cloud sync conflict, select your local save (the most recent one).
Done!

Author: Alicelel