"I heard your clan has a kekkai genkai?"
"Ue-sama?"
"Namikaze-san is fine."
"Sorry- Namikaze-sama, the Iga clan has what appears to be a kekkai genkai. We really don't though."
"Oh? Please explain, Yayoi-chan."
"Well- each blood-member of the Iga clan has a predisposition to have a high level of observation-based situational awareness. We've also got records of the average member being very good at divining, and occasionally projecting what we call "true intent"; when Raiko sings, she's projecting her true intentions. It's why her lullabies are so effective."
"Is this… observational skill of the Iga a skill that can be learned by people outside the clan?"
"Technically, yes. We have records of various friends of the clan attempting the ritual we use to awaken latent observational skills. In all cases, they go… well, clinically insane."
"How insane?"
"Um… Trying to claw their chakra-network out because they can feel it rushing through their body insane. Stabbing their ear canals out of their skulls so the rushing sound of their blood will stop annoying them insane. The thing is… every living thing that has a nervous system that allows the sensation of touch to register is aware of their chakra network. Everyone can hear their pulse in their heads. However, for the most part, you ignore those sensations because there are other sensations that are much more important. Part of the Iga ritual of Perception Expansion makes the user suddenly, violently aware of all their senses- touch, taste, smell, hearing, vision, and several senses that aren't specifically named- in all their capacities."
"Like?"
"Magnetic field awareness, for example. How do you think people with good direction sense can navigate so well?"
"Ah. So, if for example, a member of the clan had natural Sen-chakra sensing ability-"
"They'd be banned from undergoing the ritual."
"Really?"
"Being able to eat food is generally more important than being able to fully sense all the chakra of the natural world around you. It eventually tapers off enough to be dealt with, but all our records show a distinctive trend of death by malnutrition for the majority of Sen-sensitive individuals who attempt the ritual."
"Ah. So there's no way for me to do this ritual, right?"
"Absolutely not, Namikaze-sama."
"Would anyone in the village who isn't an Iga be allowed? An Uchiha, perhaps?"
"No, Namikaze-sama. Even if it was ordered of us, no Iga clan member would ever allow a non-clan member to undergo the Ritual of Perception, nor would we explain how to undergo the ritual to an outsider."
"Interesting."