The Eight Trigrams Seal on Naruto was a Sealing Technique originally created by the Uzumaki clan. After studying it for a short while, Kushina successfully deciphered the sequence to undo the seal.
"You two, why are you still alive?" Crouched behind the metal gate, the Nine-Tails watched Kushina and Minato outside, filled with intense curiosity.
"It's Chakra, isn't it! This is the Chakra you left behind." The Nine-Tails hit upon a possibility.
As for the Nine-Tails' questioning, everyone outside the gate chose to ignore it, which infuriated the beast.
Mere humans, daring to ignore me, the great Nine-Tails! If not for the obstruction of the seal, it would have long since rushed out to tear these fellows to shreds.
"Kushina, open the seal first! This fox is too noisy." Kizaru, who had originally intended to lecture Naruto first, decided to quiet the fox down in the face of its roaring.
"Alright!" After answering, Kushina looked at Naruto and reminded him with concern, "Naruto, get ready. Try to stay clear-headed and don't be affected by the resentment within the Tailed Beast's Chakra."
"Yes!" Naruto answered loudly.
Hearing Naruto's confident reply, Kushina glanced at Kizaru once more before beginning to undo the seal.
As she placed her right hand on the seal on Naruto's stomach and undid it, a surge of Chakra suddenly appeared.
A hand suddenly emerged and grabbed Kushina's right hand. When she looked at the owner of the hand, she was completely stunned.
How could there be another Minato?
It wasn't just Kushina who was stunned; everyone present, save for the informed Kizaru, fell into shock, including the newly appeared Minato.
The Kushina, Minato, and Naruto of this world all looked at the newcomer. As their gazes met, they began to process the situation after the initial shock passed.