Dragon Ball Z x Naruto
Lets say that Kaguya Otsutsuki was a refugee of another planet who crashlanded and took safehaven in the planet which is developed Naruto. She interbreeded with the local resulting in the current humans who can produce Chakra a trait which her species posses.
And one cant say she wasnt the only one to inbreed or crashlanded as other species of humanoid from foreign world passed through the very same thing. Remnant of their existance are the clans with inherited abilities due to their Bloodlines or some inherentence from their genes(Illogical hair, hair color, eyes shape and color metabolism etc etc).
Now A Millenian after that another Alien takes refuge on this planet. This one is a Saiyan who will change the world the same way Kaguya.
The Psychic Saiyan Bardock becomes the pratriach and Founder of the Saiyan Clan.
Think that every race of Humanoid that settle named their clans acording to their species name due to possibly not having last name or family name.
Bardock-Centric shift to those who interact with him. And influence the world becoming spine in Madara's side or another piece.
Set during the Second Shinobi or Third Shinobi War.
Concept: Saiyan Physology/Psychology.
Do to their super metabolism they eat for 30, also that they cant get drunked since Human alchol isnt strong enough to make them be unconscious, or drugged unless its stronger than his metabolism. But if it survives it he/she will become stroger later.
With super metabolism it would be presumed they age faster, but no they dont they stop growing similar to their 20's and keep looking like that until their 80's to keep fighting. Ofcourse if they havnt died in battle.
Their tail unables boost their power level further, train it and they have something equivalent to a third leg or arm.(Gogeta SSJ4 fights using his tail in DB Budokai Tenkaichi.) And absorb more the Blutz waves from the moon thus turning them into Ozarus/Great Apes.
No matter how pascifist they maybe, they will always wish to push their limits. A pure-blood will never give up a chance to have good fight, that is only to a half-breed is optional. And always arrogats(Goku and Vegeta in Cell's game allowing cell to ascend to Perfect, Gohan Trunks and Goten in GT with their lifes.)
A pure-blood saiyan is simple minded and stubborn to lose focus of what he/she wants and wont stray from its path by no one as they see it as an obstacle to overcome(Vegeta obssesion to beat goku and Goku obsession of Training to be stronger leaving his family-Ironically Vegeta is better father than him MEME XD.). A Half-breed on the other hand struggles however given the drive and focus.
More elaborated insight of the Saiyan Culture in Dragonball Legends. By Veema.
The Inuzuka Clan: Bardock is Alfa Male Material!
Logicall opinion: a Saiyan always will be atracted to either strongest of character being will or physical. And always will mirror saiyan's personality traits in some way.
Personal opinion: A Saiyan who will look like his 20s when he gets to his 80 and Granny who looks like 30s when she have 50, lovely couple of longetive Monsters.
Well I would sugest Create a situation in which Tsunade is the one who first finds him near the stairway to heaven-hell(Death) and the oe who is first introduced in this world.(Similar situation when Bardock is saved by the natives in Planet Plant or Vegeta pre saiyan/Tuffle) And since this might take place during the second Shinobi war and Bardock start to stand out in it possibly be putting Tsunade in a situation which she is pressured by other clan members of Konoha(Political Shit). She agrees only because she have somthing to gain which is study Bardock physology the KI which it generates and a anomalie(Where the exact spot which Kanassan Hit him and give him his psychich powers to see the future and possibly read minds as he grows with it).
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