User blog comment:Hitsuji Mamoru/Servant Creation Room 2 : Guess of the Who/@comment-4802891-20170727204532/@comment-4802891-20170731061129

Is he real or fictional?... I would say "both" depending on who you believe. His True Name as a Servant is that of a real person, but he is neither the real deal nor a completely authored character. Most historians doesn't consider him factual, some conspirationists do, and in the Nasuverse, I think he is canon. As I said, he isn't an actor but "you might be onto something".

As for hair and eye colors : forget them, it's fluff.

Here's a hint for his Noble Phantasm(s) : His sotoba shares some functions with Kaleidosticks in Prisma Illya.