I don't think we can say the knife was JUST in the girl's head.
I think we can. Her hands are full the entire scene with the tray, and the knife only appears in panels where Suu is imagining Mayu. When the art is normal, there is no knife. All of the exaggerated versions of Mayu are seen through Suu in either panels where the art changes or in memories although that could just be the nature of a comedy story.
Well, that's one interpretation. But looking at the first couple of instances of girl-with-knife, it does not look at all like that to me. To the contrary--Suu starts off by thinking about things, trying to figure a solution, then says something, hoping it will be OK, and then you get Mayu's reaction shot with the knife, which results in Suu going "Erk! Guess I got it wrong!"
So the "Mayu with the knife" images are very much GIVING SUU NEW INFORMATION ABOUT THE WORLD. So they're not imaginings or recollections. And yes, the art style does shift a bit--specifically, it shifts from simpler and smaller scale bits that ARE about imaginings and recollections, to the more detailed and stark Mayu-with-the-knife. If there is a shift, it's the knife bringing Suu BACK TO REALITY. And nowhere is there anything that looks to me like a signal that she's hallucinating; normally I'd expect that if the events shown on the page as happening are supposed to be not actually happening, there would be something to let you know.
So I really don't think the text supports the interpretation of the knife being in Suu's head.
I'd like to note that neither direction really has much impact on my experience/enjoyment of the story.
last edited at Jan 4, 2023 7:06PM