Plane of symmetry in alphabet N

[Elena14]

My teacher says that "N" has no plane of symmetry(POS). But shouldn't the plane shown with blue be POS?
I understand that a plane of symmetry bisects a molecule into halves that are mirror images of each other. For this reason, this plane shown here should be the POS. Where am I wrong?https://www.physicsforums.com/attachments/98339

 

[micromass]

Attachment doesn't show.

 

[Jody]

I'm not seeing it. The attachment isn't working, but I tried a few direct approaches, and I am assuming you are talking about $\sigma_v$ operation: