Some of you guys sound pretty naive. There's probably no country in our world that accepts ignorance of the laws as an excuse. Being used by someone doesn't matter either, you committed a crime whether you knew it or not and whether someone else gave you the idea or not. Honestly 5 years probably isn't that much for violating a border and assaulting the people who come to investigate what you're doing. Before one of you says "but it was the guards that attacked, not Nanana," who do you think spawned those monsters that disappeared on death? If she's not responsible for what her powers do, then who is?
The prison she's going to is practically a vacation spa too. By the time they've actually earned her trust and she's earned theirs, they can always let her out earlier if need be. Parole for good behavior or something. We've already seen that they're fine with reducing sentences for stuff like that with someone else... it's just that person made an ass of themselves repeatedly while working towards a reduction and she didn't get much out of it this time.