As indicated by his codename, Ypsilon is the second Perfect Soldier, having been "born" after Proto-One. She was with Ypsilon during his awakening in the underground sections of the former Red Shoulder base on Melkia. She gave him his name, and he formed an immediate attachment to her as would a child to its mother. She first attempted to teach him gentleness, but his pre-programmed killing nature emerged despite this, much to be pleasure of Albert Killy and the other masters of the Secret Society.
Under the later tutelage of Borough and Prince Kanjelman in Kummen, Ypsilon matures as a warrior. His genetically-engineered combat skills are honed to perfection, and unlike Proto-One, he remains fiercely loyal to his commanding officers.
Emotionally, however, Ypsilon is still very much a child. Arrogant and egocentric, he sees himself as the ultimate in human evolution. From his first encounter with Chirico Cuvie, Ypsilon becomes obsessed with killing him, convinced that Chirico has poisoned the mind of Proto-One ... and only his death will end her "confusion" about whom she really loves. This obsession increases from one bloody battle to another throughout Kummen and all the way to their final showdown on Sunsa.
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