In most Steam visual novels, you can change the language in the game's settings. Usually, there is an option like 'Options' or 'Settings' in the main menu. Click on it and look for a 'Language' tab. There you can select the language you prefer.
First, make sure your game is updated. Sometimes, an older version might have issues with language settings. If it's updated, try verifying the game files in Steam. Right - click on the game in your library, go to 'Properties', then 'Local Files' and click 'Verify Integrity of Game Files'. This can fix problems related to language options.