Depending on the error, you may need to follow these recommended steps:
If the screen is blank but there is no other error, it may be a steam cloud sync failure.
If you get an error about invalid date/time, this is a steam cloud sync issue - disable steam cloud and restart the game.
If there's a DrawDevice or a DirectX error, download and install DirectX End-User Runtimes.
If there's a 'Cannot convert void to Object error' or msvc error, download and install the Microsoft Visual C++ 2010 Redistributable Package (x86).
If the error is 'cannot convert given 'narrow string' to 'wide string', please uninstall, delete the folder in Steam, and reinstall the game.
If the error is 'cannot run 18+ content while streaming', please make sure you've verified you're not running the beta version of Steam.
If you do not see the option for the H content after installing the patch, please make sure you are not running Steam in beta client mode.
If you get an error on clicking Extra that includes cgmode.ksv, open your game folder and delete patch2.xp3 and patch2.xp3.sig
First, make sure Steam is running in administrator mode and the game is not running
Make sure you have ran the game at least once.
Then run the patch in admin mode
If these steps fail, make sure your patch and game copy are the latest versions
If that doesn't work, you may need to uninstall and reinstall the game
Finally, if 1-5 don't work, please reinstall Steam.
If the steps above didn't work, try the following:
Make sure your graphics drivers are up to date, and that it meets the minimum requirements.
Make sure that the game is not installed in a UAC folder.
To change rendering options, follow these steps:
Hit Alt-H (help), then A, then hit Enter. This will enable advanced settings.
Hit Alt-A (advanced settings), then V. You'll have three to four options: A for auto, O for Overlay, L for layer and M for mixer. Select one of these, then hit Enter.
If you get an error about Steam Cloud Sync Failure (Or, on loading the game, you get an Invalid Character message),
In Steam Library, right click on the NekoPara game you are having issues with
Click on Properties, then Updates.
You'll see Steam Cloud at the bottom. Unclick it. Then load the game.
If you get an error about TVP/KIRIKIRI :
Run the game in compatibility mode
Also run it in administrator mode, if possible.