Why is there a dad in the last panel? Did the artist forgot their own story? The kid can be excused, as they need to be raised somewhere, and maybe they are deported at a certain age.
Glad they didn't drag it out. I can imagine a worse author having 10 more chapters where the audience obviously knows much more than the main character.
She definitely didn't kill her sister. She's going to have lost her sister, and be saved by Shin and Kyoukai. Probably won't join the group, but will come back later on to help, maybe help heal Kyoukai in some way. Not a spoiler, just a guess.