I really need to get ready for ROTC PotLuck, but I don't want to. I might do some more art first.
Anyway. Sirin really kicks ass! Akuma and Odaku were her apprentices/adopted children (see Purity is Corruption comic to understand that part) And she's sort of hard on them so they'll do better. Senpai means upper class man/higher ranking person and is usually used between students. so if you're a freshman and your talking to a senior you'd call them (name)-senpai.