User blog comment:Halo1081/Chapter 128 and forward/@comment-122.60.6.94-20150223120628/@comment-5707992-20150223121211

It was already confirmed in the first chapter that Korosensei is from Earth. Anyway Kayano's tentacles are black and unlike Itona, whose tentacles sprouted from his hair and thus were his hair color, Kaede's sprouted from her neck. I doubt they were failures as Shiro only meant to put the tentacles in Itona's hair, but with Kayano there's speculation that she is possibly a prototype from the same experiment that made Korosensei the octopus thing he is.