The lightbulb finally clicks on over Nonoka's head‼
I'm curious whether Kiriyama is also as oblivious to liking Nonoka as Nonoka is to liking him, or whether Kiriyama knows that he likes her but he's assuming that Nonoka isn't interested in him or he's just waiting for Nonoka to make the first move. Like Nonoka, I find Kiriyama hard to read.
Also LOL to Kiriyama's blasé reaction to Nonoka asking if he's in love with his sister. He's so used to her nonsense by now.