Momoshiki, Kinshiki are underlings and likely not the main person Kaguya feared.

[Reviewing Logic]

Likely the one that Kaguya feared was this due to the left

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Also likely the dude Toneri foresaw in his vision

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Seeing as Toneri never involved himself in Boruto the Movie.

Also why Momoshiki gave Boruto that curse mark.

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Likely Kawaki got his curse mark from that man.

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This reminds me back in the day with Nagoto/Pein

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[MomoSaka]

The otsutsuki era.......

 

[Shruikan]

Looks like a brainless brute here. Where are the smarter villains like Madara or Pain

 

[Reviewing Logic]

I want to see a Ootsutki General

with a whole organization/army like want Kaguya warned about with a ton of Oostutski fighters/elites

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I also want him to have a coat cape like Rustal from Gundam IBO

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lol when I was looking at Oostutski images I came across a Hidan one

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[SixPathsMike101]

Pretty good theory

 

[NextGenNinja]

I highly doubt they were underlings, but i do think they weren't the only ones kaguya was preparing to fight.

 

[Made in Heaven]

I want to see a Ootsutki General

with a whole organization/army like want Kaguya warned about with a ton of Oostutski fighters/elites

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I also want him to have a coat cape like Rustal from Gundam IBO

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lol when I was looking at Oostutski images I came across a Hidan one

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I've seen far better OC Ootsutsukis

 

[Reviewing Logic]

I've seen far better OC Ootsutsukis

post images I need them
lol

 

[Warlocks]

Kaguya feared WHOLE otsutsuki

 

[Made in Heaven]

post images I need them
lol

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[Airi]

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Wow, I like these character designs o-o

I wish Kaguya looked like that~

 

[Darth AniCetuS]

From the last episode its clear that the otsutsukis have a major role to play.