Re: what do you think of in
I hope this helps, but Machi used Zetsu on her thread to keep track of the vehicle Kurapika was in.
So I guess it is pretty possible to 'wrap' things in a layer of In or Zetsu. With Zetsu you make the thing barely perceptible. With In you make the thing invisible and imperceptible. En can be used to detect things hidden with both In and Zetsu. Gyo can also be used to detect things hidden with In.
I agree wholeheartedly.
I think OP basically got confused. So far, the only connecting factor I can think of between Zetsu and In is the concept of invisibility or impercievability. It doesn't necessarily mean that in order to be hidden or concealed, you have to close the nodes in order to do so. Closing the nodes is the actual physiologic change that one must allow to happen in orderto be invisible to other nen users. Thats all there is. But it does not define the concept of Zetsu or In.
Ren, Ten, Zetsu and Hatsu are the 4 nen training concepts.
In the 2011 intro's (english subtitled). The 4 concepts of Nen are translated as:
Ten - Shroud
Ren - Enhance
Zetsu- Null
Hatsu - Act
Again... Hatsu... ACT.
As we all know this leads to all different kinds intricasies/applications/gibberish just to get the official concept of Hatsu (To act). For example, some people like Gon uses all Ten, Ren, and Null to get this effect. Some people like to change their aura into bubblegum or electricity or conjure chains. Some people like to call a ghost writer to write prophecies. Some people like to steal other peoples Nen. All of these fall within concept of Hatsu (Act).
In the same extent. When one says Zetsu (Null/Conceal), it doesnt necessarily encapsulates everything with the concept of "Turn Nodes: ON and Turn Nodes: OFF." It just simply means as the translations suggest - to Null and Conceal. Being able to recover from fatigue and heal yourself faster is just the bonus.
Now "In" is the advanced application of Zetsu (null). It's the same concept but just an application. Just like how En is the application of both Ren and Ten. "In" is part of the many nen applications like Gyo, Shu, En, Ko, Ken etc...
http://h-x-h.wikia.com/wiki/Nen
And I do understand the confusion. Example of people that were shown to use "In" were Hisoka, Machi, Kurapika and Bomb devil. And the thing is, it wasn't properly explained in the manga nor data books how people achieve "In" and conceal their aura. We can only speculate. Seriously. It sucks. I know. The only thing we were given was node shutting and the use of En or Gyo to detect concealed aura.
In isn't very well polished in my opinion.
I think Togashi was shooting for these concepts as a whole rather than the technical or physiologic aspects of attaining it. The confusion is normal since we're not really given a lot of validation to begin with.
Hope this helps.