You might be able to find it on popular digital game platforms such as Steam. Many visual novels are available there. You could also check out some dedicated visual novel websites. Just make sure to check the legality and safety of the source.
First, try looking on official visual novel stores. Some of them focus specifically on niche or indie visual novels and might have 'crimson gray visual novel'. Another option is to search on forums dedicated to visual novels. Gamers there often share information about where to find rare or interesting visual novels. Additionally, you can search on the official website of the developer or publisher if you can find out who they are.
There are several places you can search for the 'crimson gray visual novel'. One is on large gaming platforms that host a variety of titles including visual novels. Another possibility is to look for it in the app stores if there is a mobile version. However, not all visual novels are available everywhere. You could also reach out to visual novel communities on social media platforms like Reddit. People in those communities are often very helpful and might be able to point you in the right direction. They may even know if there are any upcoming releases or special editions of the 'crimson gray visual novel'.