The oldest of classical literature is out of copyright – anyone can do anything they want with it. More books enters this public domain every year.
And people do cool things with it all the time, or just make them available as ebooks trough Project Gutenberg or https://standardebooks.org/
So how about splitting a book into short chunks, illustrating some of them (VNs show you don't need new illustrations for each chunk), drawing the characters, and publishing it as a VN game?