No, you can post manga content as well.
However if it’s a huge spoiler, post it either as NSFW (NSFW=SPOILER) or as a text post with images where the image would be inside spoiler syntax.

I guess I should add some spoiler guidelines to the rules. I’ll do that later.

The spoiler feature is coming to Lemmy so I’m definitely hesitant to create another community just for the manga.

Also I love this artwork! Simply amazing!