1. Go to Steam, right click on Hoshizora no Memoria, then Properties. Click local files, and then Browse Local Files. It should look like this:
2. Open the rar file, and it should look like this:
3. Open the system directory in the .zip, and you will see this:
4. Copy the files from that to the folder in Step 1
5. Click to confirm the file overwrite
6. You're done!