Naruto: Me, with Shikotsumyaku and the Byakugan

A girl of the Kaguya clan, orphaned in the Bloody Mist and killed by the Hidden Mist ANBU, rose from a mountain of corpses and a sea of blood. Her mutated gray Byakugan and all-purpose Shikotsumyaku combined to give her a bizarre ability to control her own body, setting her on the inhuman path of a taijutsu ninja. Shikotsumyaku strengthened her bones; the Byakugan let her control chakra and her body; Lightning Release Chakra Mode forged her physique; the Reverse Eight Gates filled her with life; devouring Tailed Beasts gave her an endless power source and a Tailed Beast Cloak; and Enma made her indestructible… The beautiful girl, delicate as a doll, became an inhuman taijutsu monster. Her overwhelming stats and abilities, together with the terrifying contrast between her appearance and fighting style, made for a bloody, relentless Hokage story. (Not a transformation story, no romance, somewhat dark, nearly invincible, no System, and she won't play nursemaid.)