The packed morning train isn't a good place to be if you're small; a fact that high schooler An knows all too well. So when a boy rescues her from the crowd one morning, she should be grateful... right? The only problem is, he treats her like a little kid! Who is her rescuer, and what will happen when she meets him again...?
(Source: Shoujo-Sense)

Kae and Kousuke see a couple kissing at school. This make Kae get all flustered.