I have math coming out of my fucking eyeballs. 

A cafeteria is populated, but if they attack during a busy time wouldn't that close the school until further notice, so I'm guessing you meant that Kurama and Botan are somewhere isolated while this happens. They can attack after school and make their presence known by being the only ones not leaving out of the crowd, and just staring at Kurama/Botan--Kurama picks up on it pretty quickly so he tells Botan to stay close because they will use her against him the minute he lets her out of his sight. 

The big bad guy can be name... -googles Japanese names- ...Katsu? Or do we want a more dickish name, like Goshigi or Mekukiro or some shit? Anyway, I'm agreeing to 2-3, but I think the attack should be less about winning and more about Kurama and Botan knowing that the enemy knows their true identities--OR, we could make it so that their unnaturally high spiritual energy made them targets, but that defeats the purpose of this being an old enemy, and if that happened, why did he not just do this at the funeral or something? So yeah, we'll just say this attack is a message and they weren't meant to win. So Botan can't go anywhere alone outside of the school; she has nifty tools but the second this foe gets serious, she probably cannot hope to survive unless the foe sees value in their survival i.e. torture Kurama and hold Botan against him. 

Damn it Genkai, your surprises, they kill me so :C