Author's note, hello and welcome this is my first story now I would like to point out right now that. I'm not the best when it comes to writing but I promise to do the best. I can while I'm writing this I would also really appreciate it if I could be told me where I messed up instead of just flaming me.
Disclaimer I don't own Naruto but I own this plot
Summary - Something goes wrong during the sealing of Kaguya and she ends up sending Kurama's chakra, memories and consciousness back into time younger naruto the influx of chakra is too much for the seal to handle and it's forced open. Minato shows up to fix it and after having a long talk with a new fox entrusting a second copy of the seal key to him and asking him to watch over his son. (This is a harem story I have some girls in mind but I'm open to option).( He will be a sensor both negative emotions and chakra trust me this is all for a reason)
"Bijuu speaking"
'Bijuu thinking'
"Human speaking"
"Jutsu"
Prologue
"Well that could've gone better". Kurama groaned out his head feeling like he took a tailed beast ball to the face. "Ok let's recap there was a big ass war, I made nice with my container, we fought in said war. We beat I think his name was Obito who then turned around and became good. Then we turned and had to fight Madara zombie ass. Then finally my grandmother of all people shows up out of fucking nowhere and we had to fight her extraterrestrial ass honestly why all the people from my past can't just stay dead. Kurama looked around noticing he was back in Naruto's seal locked gate and everything. 'Ok so the old man sage jutsu worked I'm back in time and I can safely assume if I made it back the rest did as well that's good. The question is how far back am I'.
Kurama walked towards the gate noticing the familiar pipes along the ceiling that contained his host chakra. He touched his tail to one of the pipes to get a clear look outside his host. "Ok so it's the night naruto found out about me didn't think we'd be sent this far back but we can make do I should probably lend him some chakra just for an added kick to his clones. Kurama started feeding his chakra into naruto. A Naruto whose body while still able to hold a substantially large amount of chakra wasn't yet developed enough to handle a bijuu willingly giving him as much charka as he could handle.
"Wait something is wrong he's going into the tailed beast state. Wait I remember this back before his father during that six tails incident and before he got the key from that sensei of his. This version of the seal was just meant to keep me locked away unless it was an extreme situation. His body can't handle this much of my chakra. Kurama quickly cut off the chakra he was giving him and looked toward the seal there was a crack and it was slowly getting bigger by the moment. He watched in fear as the seal slowly ripped itself apart until it was gone and the doors opened.
'Ok the seal is open that bad but as long as I don't try an walk out or send all my chakra through Naruto won't die and his father should be here any moment to fix the seal'. And right on cue Minato appeared looking just as he did thirteen years ago he looked around trying to spot his son but all he saw was a big fox with a relived look on his face. The same fox he fought tooth and nail to get into his son honestly it was an odd sight for the young kage. "Well don't just stand there fix the seal I may not be trying to escape but he can still die from the pain of the seal being destroyed we both know this. "You're not trying to escape nor are you trying to kill me and the doors are wide open. "And I'm an ancient chakra fox whose grandmother is in the moon now that were done stating the obvious you should probably fix this seal before your son joins you and kushina something that will make her incredibly pissed at you. At the notion of making his wife angry at him something even the strongest of men fear he quickly flashed over and redid the seal reinforcing it as well. "Ok the seal is fixed want to tell me why I haven't died again yet or are we still playing the obvious game. And so the fox told him everything the future or in Kurama's case his past which quite frankly the more he told Minato the more he realized he might not believe him.
" I believe you"/"You do?"/ We live in a world with giant talking animals, Giant monster's made from energy, and humans can go around making the four elements their bitch. I can literally jump through time and space thanks to glowing calligraphy, at this point aliens doesn't seem too far out of pocket. /"Well when you put it like that its really isn't a big deal but the important part is you believe me so I'm going to need you to do me a few favor"./"Go on"/"I need the seal key that way I'll be able to safely open the gate and give Naruto chakra when he needs it and so I can talk to him"./"Done anything else"./"If possible try and modify the seal show kushina shows up the first time naruto enters the mindscape he'll probably take it a lot better if he met his mother at the same time"./ "Done is that all"/ "Yes that is all I would say leave the knowledge of the rasengan but I already know it and if I don't teach him your teacher will."/ "What about the flying raijin"/
"I've got a way around that besides naruto would never sit still long enough to learn how to write seals or learn how to use them in battle he may look like you but's he is just like his mother./"That's what I'm afraid of. I've the modifications to the seal you'll now be able to unlock and relock it at will and I've also set a timer for kushina to appear the first time Naruto does. I'm putting a lot of faith in you fox don't let me down because if you hurt my son not even death itself will save you from me".
"Naruto is my friend and the only human who has shown me and my kin kindness in a very long time we may argue but I wouldn't him in harm's way if I can help it your right to put your faith in me"./ "Then I'll leave to you Kurama". With that Minato faded from the seal his time up and his chakra depleted from the seal. "You can count on me Minato". And with that Kurama laid down to rest after his extremely eventful day or was it life honestly time travel fucks with your perception of time as a whole all he knew was he was tired and needed a nap.