>>97169Her attitude is an important part of the appeal of her breasts です.
You see, an airhead like Sanae-san doesn't understand the magnitude of her own breasts. She doesn't particularly view them as sexual, and never makes any intentional effort to eroticise them.
However this actually has the inverse effect and makes them even more erotic: by treating such ludicrously gigantic breasts with a kind of tasteful innocent modesty, she importantly leaves her breasts always just out of reach and creates a space for the viewer to participate via imagination, as all great works of art do.
The very unattainability of her breasts leaves the viewer's desire forever unfulfilled and thus able to grow exponentially forever, as opposed to the cheap disposable eroticism of normal large breasts.