Draw your wakizashi, inform them of your linage, and cut them from shoulder to sternum. Wipe sword blade, re-sheath, bow slightly, and resume your business. No need for guns.
1995, that was me. Had the full katana, but yeah...
That kind of cut with a wakizashi is a bit tricky. Might want a full nodachi for that one.
Walked around campus all day, me and another classmate, with katana. No worries at all.