OMG!!! Had a thought!

So...I thought of a kekkai genkai for Kana that she won't even know she has until later on. For now I was just gonna have her think that it's a normal part of being a ninja. Here's how it would happen:

Sometime during their time in the Rock Village (before she dies) Felix and Kana will be training or something (something where Felix has to use his chakra), and Kana notices something weird about his shoulder (the one that Eliade injured); it's not circulating chakra normally. Well it is, but it seems the flow is a little messed up. After training Kana mentions it. Felix questions it, and she tells him that she's always been able to see the chakra flow of others, and in some cases lack there of. She tells him it's how she's always known when her enemy was about to use a jutsu. Tells him that she thought that kinda thing was normal for a ninja, even though it was never mentioned in school or anything.

I thought it was a neat idea, but I've yet to think of a name for it. Unlike the Byakugan and Sharingan, this kekkai genkai is passive, it always works, and doesn't need to be activated.