Mitadake High (Halloween SP Event?)

Dual, I was the one in the Principal's office. I then ran out and locked myself in the gym storage room. After that, I snuck through the vents into the security room, before going back and killing Yoshi, who had apparently already killed Mirage in the office. Then we fought. I then ran back into the vents and into the security room, where you eventually killed me due to you having way more health.

And you can't lock the door to the security room after you open it, which I had to do to get out the first time. ;_;