User blog comment:Martialmaniac/How does "In" work?/@comment-14902757-20150716163943

Interesting..

I think MrPedroNorris' theory though is the closest.. I think that In is like a layer of aura that works as a "negative-aura" in such a way that it camouflages all the properties of nen that would be otherwise perceivable through other nen-users.. And I agree with your spectrum theory... the stronger the nen user, the stronger In/Gyo he/she can produce...

Think of In as a non-living aura which possesses the properties of certain stuff like smoke, EMP, etc..