naruto gets the curse mark in forest of death.

the 9 tails is helpful

he goes to the uzumaki mask temple and the shinigami (through the mask) tells him of what he became and powers that he now has

blessed by death he is a the
necromancer.

gains the powers of the some of the nine demon gates from fairy tail with he gains rose release (thorn curse) and disaster release (Calamity Curse)

and gains powers from the shinigami which are:
intagability, invisibility, insects to spread disease, shape shifting, ice release, magnet release, dead bone pulse, summons skeletal hands to block or attack, blood release, sealing chains, and summon skulls for long range attacks. (think yendere simulater Easter egg for under tale)

He also has a doujutsu that gives him the 5 basic elements and let's him see souls and spirits (look up kamigan gods eye naruto fanfic for powers of elements) look at next chapter for said doujutsu design.

Harem is
Naruto
X
Karunia
Hinata
Hana
Gaia (fem gaara)

I am re writhing sommeones else's work and making it my own so it is weird. a majority of the stuff was from the original rise of the reaper from fanfiction.net so it will be quick updates but I am adding and changing stuff that happens. sorry if it's weird wordings.