Most people here are still failing to consider the events of this story outside of just one framing. Depending upon which frame that is, they see Chitose as behaving badly, Itsuki as behaving badly, his brother as behaving badly, Kaoru as behaving badly, or some combination of these. Such nonsense! Especially in the case of Kaoru, who has always just been admiring of Ituski as an artist and of Chitose and Itsuki as a couple.
Meanwhile, what has most struck me about this story is how very little creativity figures into its notion of art. That was almost explicit in this chapter, and is also reflected in the competitive exercises in which the students are engaged. Indeed, the mangaka just used a bunch of photographs to represent the work of the students, and those photographs aren't even processed with different filters; they are simply taken from different viewing angles.