When the kiss breaks, Sendo can't help but let out a small little sigh. But then the realization of all of this started to set in on him and his face turns a little bit red and he tries to hide any embarrassment.

"S-Saya. I didn't..I mean, I may notice a lot of things, but..I never.." How could he have known that she liked him in this way? She never made it obvious. At least not that he was aware of. Saya just must have done a very good job of hiding it, that's what he was certain of.