User blog comment:EmirK/About Kihara Amata's son and espers in Kihara family in general/@comment-5230978-20130712164814

It would great if Pierce was both a Kihara and the Number 6, but, if he is, he must have changed his surname or even the name, because otherwise Tsuchi and Touma should know his identity as Kihara.

Ah, just a thing: Amata isn't Gensei son. We don't don't know their family relationship.