The Most Qualified Among Them

Not surprisingly Shiro was able to figure out who Kayano was all along after observing Class E throughout the run of the assassination project.

Having realized her true identity through the subtle reaction she’d made during his first introduction to the class, he was able to decipher from his assessments that she was none other than Yukimura Aguri’s little sister, Yukimura Akari, who was able to steal their research during the confusion of the accident; 

which most likely implies that she was there during the time that her sister had died.

Given her level of intelligence, plus the fact that she possesses an overwhelming tenacity to have been able to keep up this false pretense for a year, there isn’t a doubt in his mind that she is the most qualified among them to be an assassin capable of killing Korosensei.

It looks like what the class was missing to become 'true' assassins was something far more simpler than the simple motivation of money or desire to be acknowledged.

Who is the REAL Kayano….?

((Shit really hit the fan at Mach 20 for these guys.))

Still feeling overwhelmed by this shocking revelation that such a person was among them this whole time, a few of the students make an effort to piece together what they can to try and make sense of this conundrum that they are now facing.

While Itona informs the group that it’s already incredible enough that she has been able to get this far without maintenance-considering the fact that possessing those tentacles is akin to having one’s brain eaten by a million bugs-

((Oh man. And to think that’s what Itona went through before, and what Korosensei goes through EVERY.SINGLE.DAY.))

Mimura turns the classes attention to another sensational clue that he’d managed to find after picking up on something that was familiar about her; which I assume was her voice, since it looks like that was what he reacted to when she lost the façade of Kayano.

It turns out she was a prodigy actress from a young age who was capable of taking on a character so flawlessly that one would never be able to recognize her from her previous one.

A Narrow Escape

Luckily it would seem that what Bitch-sensei had often warned Class E about professional assassination assignments continues to ring true even now.

No matter how perfect the plan may seem on paper, in practice it’s a whole different story when considering the fact that there are likely at least two or three unexpected factors that can cause things to go wrong.

And in Kayano’s case it was in the fact that she didn’t consider the possibility that he had a few trump cards up his sleeve in case he was in serious danger-like in the Okinawa trip.

Taking advantage of her confusion, and the fact that she’d neglected to fortify the passage with something to prevent him from escaping, Korosensei barely manages to flee from what would have been a brutal-yet quite impressive-assassination.