Sasha's still not used to how brightly colored everything is here.
He's not used to anything, really, not how easy it is to find enough to eat, not how cheerful people seem, not the way they interact with one another ― if there's any subtext other than "you're evil and I don't trust you" behind anything anyone says, he can't read it. It's only been three weeks and while he's figured out his way around the school and its too-empty corridors (and that's another thing he's not used to, the space, and how clean and open and bright it is) he's still kind of lost.
Which is why it's such a relief when he looks around and realizes that he keeps seeing one boy (Kaleb? something like that) following another (Li Chen, Mulan's son) around in exchange for Chen glaring at anyone who tries to mess with Kalev(?). That's an interaction he recognizes, and if there are gangs here that don't have Harry Hook in them, Sasha wants in on one of those.