she was not a real person to begin with, and Sunao can just summon her replica, Nao as any time she want.
As for why the personality change is because both Sunao and Sanada think their replica didnt feel pain like they do so they kind of treating them like an object not as a human who can feel...
i mean they aware of themself of clone, and not a real living person who can just disappear and re-appear, i think she will be fine if real Nao summon her again it just the memory of the crash still remain
but still that was so sudden
true, but people tend to be single minded, so it is not suited for everyone, personally i like how the arthor paint every character in their personal view and that how basically life is, everyone have their own mind and free to voice their opinion.
i just wish that those opinion doesnt stop...
is it just me or the sister really do sugar papa thing? i mean she seem familier with semen and even go to remote island without carry much thing like hentai plot