Dr. E99 is the mascot of the experiments on Katorga-12. He's seen on several public service announcement videos in the schoolhouse and starting docks explaining how useful and/or harmful Element 99 is to people. Dr. E99 appears as a man with the E99 logo for a head.
There are several notes left by Dr. E99 in the school building telling children to wash their hands after using the restroom. This implies that Dr. E99 became the Russian "Uncle Sam" on Katorga-12. This is further shown by a video showing Dr. E99 leading the Soviet Army/Spetsnaz in the defense of the Katorga-12 secret facility.