Sasori hadn 't known, of course. One never knows one 's soulmate for absolute certain until the day they die. If he had given any thought to the matter Sasori might have assumed that he wouldn 't even be able to tell when his soulmate passed away. He 'd spent years perfecting his own inanimate body; surely there wasn 't even enough humanity left in him to feel such a strong soul connection? He wasn 't even truly sure he had a soul anymore.

That assumption was proved incorrect in perhaps the worst way possible. He hadn 't dealt the death blow himself ' that 's what he made his puppets

for