@matrix
>but as far as I can tell there's nothing actually being said with this
And this is why these people are 100% autistic. That image actually conveys a lot. It conveys that this faction, whoever they are, are some very evil, sick and twisted individuals. They are unequivocally the evil doers of the manga, and it is very important for the heroes to defeat and kill them, cause otherwise they will continue to commit atrocities.

That image is not supposed to be "entertainment" in itself. That image is supposed to make you feel sick to the stomach, maybe even anxious or terrified about how your favorite characters will manage to survive an encounter with them. There's not really anything "entertaining" per say about feeling disgusted by something, but art is not always about the "ha ha, that was fun, I want to see that again" MCU Avengers type "entertainment". Art does include being happy and excited, sure, but it also includes sadness, sorrow, anger, rage, disgust, revulsion, offense and many other emotions.

It's ironic how well this art worked on these individuals in triggering a feeling of offense and revulsion in them, but because they're so god damned autistic, they're unable to correctly identify that the perpetrators of the fictional crimes they hate are the fictional characters, and instead blame the author, and direct their outrage at him, instead of directing their outrage at the fictional characters.
Imagine if people directed their outrage they felt when Voldemort killed Harry's parents at J.K. Rowling instead of Voldemort. I hate that I had to give a Harry Potter example, but maybe this is the only language such people understand.