I sincerely doubt that >>10687763
is the case. "A" Red Man, possibly. "The" Red Man, no.
She was TINY when the Red Man first appeared (and embedded the shard into Ganta's chest), there were also scenes showing the Red Man being restrained heavily deep inside the complex - why now is his armor in the Chief's room, unworn? She also hasn't been directly shown using the same powers as the first Red Man.