Mr. Parker is a supporting Role in Butterfly Effect.

He loves his work and is very engaged into bringing the best out of his students.
As his classroom teacher Mr. Parker tries to get Haru to sign up for extracurricular activities to make more friends, as he is concerned that Haru might shut himself in. 

He is teaching Biology and Math. He is a nature loving, down to earth guy. 
You never see Mr. Parker without some tea or teacan nearby. 

He absolutely hates it when students are late to his class, but he is okay if they 'forget' their homework once in a while.