Oh, just you wait, Tsuzuki. You'll learn.

"Reincarnated? What...no, wait, I remember now. That's the idea them newfangled Buddhists were tryin' to teach, I heard."

For Buddhists to be "new," it might have given some picture of just what time period Gan Ning actually hailed from. He wasn't terribly interested in religion himself, neither Confucian nor otherwise, but he was curious. Knowing he was talking to someone dead, or formerly dead, or a ghost, something, made it okay to wonder.