I can't imagine the pain these children are facing everyday. Like, having your closest ones going to the battlefield and return like a daily routine and you know someone's life is going to vanish. It is painful when you think you're prepared to suffer the loss, but still, you couldn't accept it. Even me reading this still haven't grip back the reality that Seiran is indeed gone...
I feel so sad for Ari... and even sadder for that one senpai too, they suffered a great loss in their life. But that's that... I know Mimi wants to make her friends happy as well, by telling Ari about that one forbidden magic. Ari could had accepted it for her own desire, in the end, I feel relieved that Ari chose not to follow Mimi. If Seiran was reanimated and became immortal, it would hurt her in the process of watching Ari die one way or another, be it on the battlefield or death bed.
Thanks for the translation. Merry Christmas to you all!