I want to point out that Chiaki said that Harumi's mother was just as gorgeous as Harumi... Even though the mother doesn't have nearly as big a bust. It seems like her usual awkwardness, until you realize that boobs aren't in fact her only metric of measuring beauty. That plus how similar the mother and daughter look in general (boobs aside of course) likely means that Chiaki was complimenting Harumi's appearance also on a basis outside of her breasts; those are just a bonus.
It ain't much, but it's something, dammit. (Also, the above paragraph is probably the weirdest thing I've ever found myself writing.)
Just in general I'm liking how surprisingly decent Chiaki was this chapter. Her usual boob addiction was probably a motivating factor in her coming to visit, but I also got the feeling that she was legitimately concerned as well. I hope to see this trend continue...