My girlfriend and I saw you across the bar and we hate your fuckin' vibe bro, we're gonna kill you

He was completely obsessed with her and she was mean as fuck, they had a perfect dynamic I think.

Miyuki left the land of iron because her father was a fucking scumbag and her mother was a wise woman that wandered into the snow to die, she came south looking for something but she never found it.

Sakumo was the last remaining son of hatake Hisoka, the woman who allied the land of fire hatake with the leaf village (and the one who banned cannibalism as a funerary practice though I would just have all of you know she signed the decree rolling her eyes and making a jerking off motion at Uchiha Madara). Most of the other Hatake had died or disappeared or married out of the family.

When Miyuki was captured, the Iwa nin that killed her pulled out her teeth and made jewelry out of them. Iwa is one of the few places the Hatake diaspora was like. Actively hunted down in (they thrive in Kumo and are deeply intermarried with a bunch of founding clans actually but the point is they traveled everywhere), and Iwa knows that the most egregious humiliation to a Hatake corpse is removing the teeth. Then they cut her into pieces and sent those pieces back to Sakumo as a taunt, and that wasn't considered an act of war because TECHNICALLY even though she'd been doing missions for the leaf, she was a foreigner and not a citizen.

Obviously Sakumo is pretty torn up about this. He buries her according to the clan tradition (open air funerals, he put the pieces that were sent out at the edge of the woods for scavengers, but when he got her head and it had no teeth he cut off one of her braids to turn into a bracelet he always wore and then he buried her head so the wolves wouldn't see her toothless) and explains to a three year old Kakashi as best he can what happened to her.