"Zimmerman," with keen interest, looked at Charles for quite a while before saying, "I detect a very familiar scent on you."
"Are we very familiar?"
Charles shrugged and said, "My fiancée is your sister! Would you say we are familiar or not?"
If Princess Akso were to marry the old Emperor of Brittany, Zimmerman would indeed be Anne's brother. Even without that relationship, Anne's mother is the eldest daughter of Julius Axel VI, Zimmerman's mother, and Princess Akso is the old emperor's second daughter—both are siblings, making Zimmerman Charles's bonafide first cousin.
Charles truly wasn't telling a casual lie; he was quite honest.
Of course, he was certain Zimmerman wasn't familiar with the "scent" on him because of Anne. That familiarity either sprang from Menilman or Princess Akso.
As for why, he hadn't had any close encounters with either woman, so Zimmerman's detection could only be attributed to some kind of supernatural ability.