I just recently bought
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and for some reason starting it up just gives me a blank black window. I've tried waiting to see if it's just slow to load, I tried redownloading it, and I made sure my system locale is set to Japanese, but still nothing. The circle's previous game didn't give me any issues so I'm not sure what is going on.
I'm supposing you got the minimum requirement in CPU, memory, OS....
First, try moving the game folder to the Hard drive root folder (like C:\).
If it work, it mean the game path was too long, move it where you want but make it shorter.
If it still don't work, rename the game folder. Make it short (just to test), remove any syntax, number and non local character - like JP kanji or Cyrillic letter on a latin letter computer.
If it work, it mean your computer was unable to read the file because the data adress was messed up by a foreign symbol.
If it still don't work, I can only see 3 other possibility 1) you got an old save file (trial ?) blocking the game. Delete the game save folder and retry
2) your AV is bugging it out. Try putting a temporary exeption for the folder
3) The game actually need you to use some JP setting, tring starting the game exe in forced admin mod using a local emulating tool (NTLEA / LE), while maling sure you're ste on JP timezone.