I had a hope in me that this manga wouldn't go the generic yandere route and I'm so glad to have it fulfilled. Kisaki breaks from the stereotype by leaning more on the obsessive side of the archetype than the violent, something that is unfortunately uncommon, and the author used those expectations of how a "typical yandere" would behave to build tension and subvert it with something that is still intense and creepy from an outsiders POV, not losing momentum and readers' interest by keeping it somewhat fresh.
Also something I notice from discussions in other platforms is that some readers don't seem to find her behavior this chapter creepy, but I think that comes from the fact that it's really hard to portray how intense and creepy it is to be stared at for HOURS in a few manga panels.
tl:dr: this is my favorite chapter yet and I love this manga so much it's starting to become an obsession.