I was just wondering if it'd be safe to use a visual novel as a related text. Not sure what the markers are going to think of them (since I assume they'd most likely have never heard of the term, let alone recognize them)...
Not a problem. For my second related text (ie. backup if they ask for two) for Module C, I have a poster, which is even more visual than your text. Just apply the same (high) standards for this text as you would for your prescribed text.
Not a problem as long as you can get what you need out of it (relate it to your prescribed text and analyse it), imo most markers probably would know of them, there's probably a reasonable amount of students that write about them.
But yeh just make sure it does relate and you can analyse it well.