If something blocks ALL attacks...

[Vegeto30294]

Yata Mirror

Impervious to any any all contact with the shield.

Lets say Minato/Tobirama marks Itachi before he activates Susano'o. He can still attack Itachi from inside, making the Yata Mirror useless.

Or Kakashi gets behind Itachi and uses Kamui

Or Gaara uses the ground beneath Itachi's feet, where Susano'o itself isn't guarding.

 

[Sennin of Logic]

Impenetrable.

However, give people a break. There's been broad, sweeping statements the manga has made that aren't correct like Orochimaru's sword being able to cut through anything. The 7 swordsman. It's not unreasonable to have the view that yata has limits.

 

[The Necromancer]

Kumai
Give me your definition of: "There is No defense against this jutsu No matter what

OR

Raikiri
Give me your definition of: A famous blade that can Cut through anything

I place Yata's hype above those, as the yata mirror is not simply a jutsu or item, it's an ethereal blade from the spirit world.

 

[KCMNaruto]

It can be invincible for now , but it's hype can be contradicted soon If Kishimoto follows very closely Japanese Mythology, as you can see here:

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Yata Mirror was Kishi's inspiration of Yata_no_Kagami, The sacred mirror that is part of Imperial Regalia of Japan.

Interesting fact is that: "The Sacred Mirror was burned in fire", maybe that would be refference to Amaterasu being able to burn Yata Mirror...

According to Japanese Mythology Amaterasu Omikami(God of Sun) gives Yata_no_Kagami to her grandson, that could suggest Amaterasu Omikami as creator of this shield.

Even more interesting fact is that Yata_no_Kagami(Yata Mirror), Ame-no-murakumo-no-Tsurugi(Totsuka Blade) and Yasakani-no-Magatama(necklace with six tomoes worn by Sage of six paths) were The three sacred imperial treasures, this could be possible suggestion of Kishimoto to shows that Sage of six paths created Yata and Totsuka as well..., However he lost these weapons somehow or hide them. However I believe the necklace Sage of six paths is wearing on his neck would protect him from Yata Mirror and Totsuka Blade's power.