ask me anything

^Exactly.

C'mon KYF, If Minato was truly a sensor, he would be able to track the Kunai every time kakashi takes a step like GPS. Instead Minato was clearly saying that the Kunai "flying" (read:being thrown), was a trigger to alert him that kakashi was in danger.

Creating seals with trigger mechanisms isn't really that hard to do by the way. We've seen it done numerous times already. Exploding tags are one example. Danzo putting a seal on Sai's tongue that activated when certain info was about to be said, is another. The spirits of both Minato and Kushina appeared inside naruto so far due to kyuubi related triggers. The scrolls from the chuunin exam were triggered to react negatively if both weren't opened together.

Blah, Blah, Blah. I'm sure there are even more instances then those I just mentioned. The point is, it's ridiculous to assume he's got some sensor related hax that was never even hinted at, when it's far more likely he simply added a relatively easy little trick to the kunai to be able to sense it's use.

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