So Mahito destroyed Nanami’s body, and the body is the shape of the soul, and Mahito’s power is to change or do what ever he wants to a soul including destroy it... He didn’t just kill Nanami’s body, he obliterated Nanami’s soul... Like not only is nothing left to bury; there’s nothing left to move on to a better place either. He’s just gone, obliterated. No soul left to reincarnate or go to heaven or be one with yu or any of his other loved ones in death. No soul to come back to guard anyone as a protective spirit. None of it. His essence was ripped to shreds.

“ Yuuji Itadori. Do you know him? I need to find him. There isn’t much time—they’re coming. ” 

before sugaru is killed (prior to the brain guy taking over his body), nanami runs into him one time. it’s just random, or perhaps not, they meet at a random little neighbourhood park that nanami is at early sunday morning like 5:30 am early in the summer and he’s feeding the koi  and ducks and stuff and sugaru shows up out of nowhere and sits down next to him at the bench at the edge of the pond and they haven’t met each other since that day in the morgue before sugaru went rogue and at first nanami doesn’t even say anything and neither does sugaru and then nanami hands him a part of the loaf he’s been breaking up for the animals and they just sit there in silence for a long time before either of them says anything and then nanami just softly says ‘i don’t blame you’ and just looked right at sugaru for a moment before turning his attention back to the pond and they just sit there for a while longer and the park starts to fill with morning joggers/runners/walkers and they run out of bread and nanami gets up and looks and sugaru and says ‘i’m sorry things turned out this way ..... for all of us’ and when sugaru stands up as well nanami gives him a heartfelt hug and then just leaves. ‘this time, i won’t tell him you’re here... but i can’t promise that if i see you again, sugaru. you both were always the best of us’ and then just walks away and goes home. and that moment just exists for him beyond anything that happening beyond good guys and bad guys, just two old friends who lost someone they deeply cared about reconnecting just this once before having to acknowledge the systems they’re a part of.