She really isn't. To make matters worse, the person Naoto runs into---

"Oof!"

-- is shorter than her, and also blue-haired. It's perfectly understandable not to have noticed her. Even so, now Kazumi is flat on her tail, rubbing one of her temples after having been bonked into.

"Um, hey, whoa, hold up! What's the big idea?"

... She wasn't even going the right way. Kazumi, what the hell.