For all i know there isn't a real proof about the existence of an arsonist but excluding other neutral killing roles, the only one that remains is the arsonist.
Anyway for me who is lying here is Hypurr, i don't have real proof but after reading again all the posts, Lia voted for Hypurr and then he said:
"Besides, it's a 5v5 now. What do we have to lose but another night to pass by? I'm pretty sure the town has a good chance on finding a scum now. If it gives you an idea of whom I'm suspecting, I'm pointing my finger toward the ones that immediately went after me as I suggested the massclaiming."
And after he voted for Lia, where i remember to you thar she didn't want to say which her role was. What i want to say is that probably Hypurr was afraid to be discovered from Lia, so that's why he choose to kill her; at least that's my theory. I know that he couldn't have know which role Lia had because she didn't roleclaim but i think everyone thought she could had an important role. So yeah in my opinion Hypurr is mafia, again i don't have real proof and i'm basing myself on what happened the last day phase and what could have happened in the last night phase. If i didn't explain it well, tell me and i will try to say it again. [Eliminate] Hypurr