Once you first enter your classroom on the scene titled "Enter Stage Left", a picture is shown, panning across everyone. Back one, and one to the right (from our perspective) is a guy that looks -vastly- different from everyone else in the room. He's larger has a different facial style from the typical anime faces and his hair is much shorter than everyone else's. That, and it looks like he's having a heart attack, which is rather jarring with School Days playing.
If this has already been answered and I'm just going to be pointed at and laughed at, I probably deserve it.

This is my first post here, and the appearance of this guy made me want to ask this. I've noticed him on previous playthroughs, but never got the energy to make an account here and ask.
Here is a picture of the scene in question. It's a small resolution, but he's directly behind Misha from this perspective, or one seat back and one to the right from where we're at.