Sunburst has absolutely never experienced zombies out of reading about them in books. Dealing with them in 'reality' is a hundred times worse- and he is absolutely not prepared for them. He's not exactly combat prepared, he's the research guy, he leaves the battles to the girls.

So, he'll be galloping away from the things in a panic. Climbing a tree is not really an option, but HIDING behind one absolutely is. It's her screaming that makes him look up.

"Mikan? Uh...is that you?"