Challenge

What if kyubi wanted the sealing to happen but for different reasons? What if the demons had there own prophecy. That an innocent soul would be sent to hell given to there Queen under the sin of pride and be her son and free them onto the land of man.

What if during the sealing Kyubi immediately overloaded Narutos coils killing him but because there souls are connected she was able to take him to her with hell to raise. As a innocent soul he is able to open the gates of hell from the inside and free them.

Kyubi condemns Minato with not being able to die so he has to witness the gate opening in 13 years when his son comes back. Because the seal failed the shigami cant take his soul. Only the sould binding was successful.

Minato sinned when he fought her was pride. Pride to use his son in the seal so hes forced to see the price of his pride yes he saved his village in the short term but after 13 years the entire world will be doomed.

Kushnia does die but Kyubi condemns her to live as a spirit to never know rest that neither heaven nor hell will take her. Her sin was sloth because she was too long in making the decision to stop Minato from using her son in the sealing after his bullshit speech she gave in even thought she knew he was wrong.

Kyubi torments the two of them briefly before returning to hell with naruto. Showing them visons of alternate timelines where she was sealed and what happened to Naruto. His completely shitty life. She also shows them visions of his life with her and it really is a better life for him. Hes treated as a prince in hell literally.

Minato and Kushnia try and gather forces from both heaven and earth to stop the invasion and hopefully rescue there son from Kyubi. They will try and gather holy relics and weapons and try and enlist the aid of nephilim (children of angels and man) that are in hiding as they want no part of the bloodshed of man. The also try and enlist Priests and monks (Hiddan and Chikku working together would be a riot.)

Kyubi also reveals that she tricked the Uchia into thinking he controlled her when she actually was using him to free her and eventually find the soul she would need to open hell.

By giving the Uchia the eyes of greed she knew valiant men would try to stop him and eventually lead to the soul of a pure heart. Ie someone that was ment to have Messiah like potential.

Madara sees this happen and drops his world domination idea and tried to help them to cant rule a world if overrun by demons. Even Orochimaru helps.

As a added feature

Demon laws prevent them from attacking a innocent unless attacked first ie if you do them harm they can attack back so when the ninjas attacked the approaching kyubi they gave it freedom to attack. Now here the work around if you're standing next to a demons target that's not its fault if you get caught in the crossfire so that why demons make massive area effecting attacks they hate humans and use this rule as a means to circumvent the rules emplaced upon them during their imprisonment. Once let out of hell though those rules won't apply.