Straight up makima isn't dead. She seems like too seasoned a devil hunter that she would let her guard down to the extent that regular people with guns could sneak up on her plus we don't know what devil or devils she's contracted with yet.
Also i don't know how they got guns there unless there working with some internationally, but then again since that guy is yakuza he probably has connections. I also wanna know how many lives it took from aki. I wonder if it takes years per stab or if he has to do the whole combo for it to take effect.