She can tell, just by his demeanor, that this had to do with the accident, or just being unknown to someone he'd called a friend. She'd already felt that herself, meeting Akihiko and Mitsuru again. But her brother doesn't have the advantage of being entirely too talkative and energetic. She already can tell he doesn't have her habit of going on about trivial things, all to keep the mood up.

But that just means she can help him out instead. She pokes him in the arm, and then actually grabs it to guide him a pace closer to herself and Shinjiro in formation. "It's okay to give him a hint!" Even if it's not the real subject, there's plenty of happier things he could talk about. "Tell Senpai something interesting about yourself."