I don't think it's my place to critique another player's signup, but I will say that I have no idea where you're going with Yamato or what role you intend for him to play. You have an idea somewhere in there, but it's almost impossible to pick out among the non-sequiturs and vagaries in the bio and personality sections. Why does he need [b]Z[/b]en to stay awake when people are talking to him, especially when he himself volunteered for a service role? Why was there an 'intellectual minority' studying him? What makes him anomalous?

From a story perspective, though, this is more important: What are his goals in life, and what will he be striving for in the roleplay? If his one and only goal is to protect the Mitsumine heir and he's already doing that, he has nothing to aim for, and no reason to be involved with any characters aside from Ryuunosuke. The charm is a possible hook, but none of our characters have reason to know his mother or recognize the charm even if they were to see it, so that would have to be a hook explored by you yourself, or potentially by Sylph as Takeshi. 'Strong, silent type' characters are very hard to play in ways that make them interesting to write for and for other players to interact with.

Just my two cents.