Needing to test how durable Akira was, Reia decided to take the role of doing the tests as she didn't trust Echo to not go overboard.
First, Reia tried non-infused essence strikes with her sword and as expected her blade bounce right off. No matter how strong the cut would have been, it didn't leave a single scratch and she was more worried that she would snap her sword.
They then moved on to small zaps of essence which also seemed to have no effect. However, as they increased the intensity, Akira needed to actually focus more mutant slime on that body part.
It was still a natural reaction, but if Akira did not actively try then he would feel a slight burn. It also revealed a part of his body meaning the more he focused on one point, the more he exposes himself to other attacks.
