@Richman I shall respond in time, with a wall of text.
I like how Chako intuitively is able to piece together on her own the relationship between him and his teacher, and the fact that it not only is unhealthy but that she's the one that Reiji was referring to earlier. Chako isn't an idiot, and she can easily judge based on how Ms. Shiba reacts that something is very, very wrong about their relationship. Part of it was that she not only sees Reiji and her relationship with him in this idealized state, but that she views herself with this messianic complex, and that anyone that gets in her way is only doing him harm.
The nonverbal communication alone in this chapter is amazing. The fact that the only difference between Shiba's death glare and her loving eyes is whether or not it has reflection in them, specifically Reiji's, speaks volumes about her dichotomous nature and how easily she can go full jealousy or yandere mode. It's very intimidating juxtaposition. What's more interesting is that Chako's eyes do the same thing later in the chapter, indicating the same drive when Reiji says he doesn't want to be saved, which, given his circumstances and that the last person he asked that in haste ended up forming a very toxic attachment to him and manipulating him into sex, I can imagine why he would see any form of help as a bad thing. It's not that he necessarily thinks that the person he's asking help for is bad, but that is life is a corrupting influence that drags them down.
I'd also be curious to see how Shiba interacts with Gen, given they both have that yandere vibe about them, and that if Gen finds out about Shiba wanting to abduct him or run away with him, the two would inevitably turn to very heated conflict.