User blog comment:Martialmaniac/How does "In" work?/@comment-26850787-20150625023730

Zetsu stops the flow of aura whereas In renders it invisible. The best example is Kurapika's chains: He conjures them, so if he used Zetsu it wouldn't work. Thus he uses In to make them invisible.

From a technical standpoint I don't recall/know how In works. The fact it can be seen through with Gyo is a nice aspect but makes things a little more confusing, to me at least. I like MrPedroNorris' theory though. Gyo is concentration of Nen on your eyes so your vision becomes strong enough to see through the camouflage layer.