Right as Akira made contact with Klein's body, he felt this pull, and the essence within his body entered Klein. Reia kept a keen eye on them, ready to pounce if anything she deemed suspicious happened.
Klein, feeling the essence spread through her body, found herself almost in a trance. Her body squirmed as the heat spread throughout her body, causing her to almost moan out of comfort. She knew Reia wouldn't respond nicely to it, so Klein covered her mouth, trying her best to stop any sound coming out of her mouth.
However, it was quite evident by her actions what was going on, which prompted an annoyed look from Reia.
Akira, on the other hand, did not feel much other than the syphoning feeling. He was impressed that Klein didn't die whatsoever, especially since this was his corruption, which was most likely also fused with a bit of the mutant essence.