4 reasons hashirama couldn't have been under a genjutsu .

[moyo]

Kabuto wasn't aware until he noticed his horn grow back, before that he thought it was all real

Also that panel where you see Madara's EMS, was hours before he got killed

if you are talking about when he's ems was shown he couldn't have used izanagi becuase

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obito states it can only be used for a brief moment.
those who posses both senju and uchiha powers could perform a full izanagi.

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at the time of the fight madara did not posses senju dna

 

[Lightbringer]

if you are talking about when he's ems was shown he couldn't have used izanagi becuase

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obito states it can only be used for a brief moment.
those who posses both senju and uchiha powers could perform a full izanagi.

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at the time of the fight madara did not posses senju dna

then how do you explain a whole clan of Uchiha utilizing Izanagi....so much so that they needed to develop Izanami to counter it. I doubt they all had Senju DNA

Also Obito never stated in those scans that you needed both Senju and Uchiha DNA to use Izanagi....Obito used Izanagi for 10min during Konan's fight....that's not a brief moment

Obito also in that page states that Danzo wasn't able to control senju cells, and only utilizing an incomplete izanagi

Uchiha DNA only=Incomplete Izanagi

Senju + Uchiha=Complete

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[Almighty Ra]

I just was correcting that u stated Hashirama wasn't a senor type when he indeed was..Not to the level of his brother but he was one so he could have sensed the genjutsu ..Is it possible he missed it yes but it hasn't been stated yet we are all assuming and theorizing what we think it could be...I agree it could be but we still don't know yet

 

[Lightbringer]

I just was correcting that u stated Hashirama wasn't a senor type when he indeed was..Not to the level of his brother but he was one so he could have sensed the genjutsu ..Is it possible he missed it yes but it hasn't been stated yet we are all assuming and theorizing what we think it could be...I agree it could be but we still don't know yet

That's why I'm reserving my judgement until Kishi reveals it

But I definitely have a feeling that foul play was involved

 

[Shadowslayer]

if you are talking about when he's ems was shown he couldn't have used izanagi becuase

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obito states it can only be used for a brief moment.
those who posses both senju and uchiha powers could perform a full izanagi.

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at the time of the fight madara did not posses senju dna

is Anyone else not noticing the fact that Hashirama had faced Madara with the Eternal Mangekyō before, and multiple times before when Madara had the regular Mangekyō and the regular Sharingan. So he has faced Madara's genjutus before and beat them, so to say that he wouldn't know that he was in a genjutus is idiotic.

 

[Almighty Ra]

That's why I'm reserving my judgement until Kishi reveals it

But I definitely have a feeling that foul play was involved

I personally believe there was a third party involved that was hidden somewhere up on the cliffs from Hashirama's reaction when he killed Madara..

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With his sensing abilities i think he noticed something or someone up there.I also want to know what really went down but till it's revealed we can only theorize and pass the time till then

 

[Great Sage of Uchiha]

sage mode gives one sensory abilities

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naruto was able to sense the juubi's chakara because of sage mode.

even kabuto became a sensor.

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Sage mode only gives you sensing abilities while in sage mode, I thought this was obvious.
J-man
Naruto
and
HAshirama are not sensor types PERIOD