Naruto: Naruto Is Still a Kid, So Why Has the Fourth Great Ninja War Started?

[No System, Pure Genius, Master of All Five Elements, Yin-Yang Eye Techniques! One Female Lead, a Different Kind of Hokage World!]

I transmigrated to the Hokage world, right? Something's not right here, is it?

Naruto's still a kid, so shouldn't this be a rare time of peace? Why has the Fourth Great Ninja War started?

Wait, Minato defected?

And Obito didn't defect?

Then what are they fighting for this time?