Mitsuko: Die, ugly.
Kyouichi Motobuchi: If I survive, can I go home?
Teacher Kitano: Yes, but only if everyone else is dead.
Shuya: I am weak, and useless.
Shuya: But I'll stay by your side.
Shuya: I'll protect you.
Teacher Kitano: Life is a game. So fight for survival and see if you're worth it.
Niida: I'm in love with you, for real, from before.
Chigusa: Wow, great. Wash your face and try again, if you survive.
Niida: Wait, you're a virgin, right?
Chigusa: Piss... me... off. God, did I just hear this idiot right?
Chigusa: Come at me. Every inch of me will resist you.
Teacher Kitano: So today's lesson is, you kill each other off till there's only one left. Nothing's against the rules.
Satomi Noda - Girls #17: Ouch! It hurts, you assholes! I'm bleeding, damn it.
Shougo Kawada: There's a way out of this game. Kill yourselves together, here, now. If you can't do that, then don't trust anyone... just run.
Teacher Kitano: Here's your list of friends in the order they died.
Mitsuko: What's wrong with killing? Everyone's got their reasons.
Shuya: How should I know? I don't know what any of it means.
Chosen answer: Kawada hacked the system, learned about the collars, and transferred voluntarily to the class he knew would be participtaing in both versions. The only difference is when he transferred: in the book, it was right after his win, and in the film it was just for the battle. Shuya never hacked anything in either the book or the film. As to why the change was made, I can only assume that, given the shortening of novels involved in film making, it's easier to make Kawada a complete stranger than a loner that the kids recognize.