Classified laboratory X139. Two female laboratory assistants conducted an experiment on mixing two substances to obtain the substance R-573. A young trainee girl, with blonde, square-cut hair and glasses, carefully mixed two substances from test tubes, and as a result, a green, slime-like substance turned out. However, the next moment, a slimy hand appeared from the Petri dish where R-573 was located, which abruptly grabbed the young intern, after which it clung to her and completely enveloped her in green slime. The green slime on it began to take on a humanoid form, and the intern meanwhile dissolved into this slime. After that, the slime began to take on the shape and features of that intern girl, with her figure, face, and even hairstyle. Then, R-573 simply regurgitated the undigested skull of the intern girl, and immediately disappeared through a drain hole in the floor